Serena Williams' quest for a record-equalling 24th grand slam title has been delayed again after being overpowered 6-3 6-4 by third seed Naomi Osaka in the Australian Open semi-finals.

Stuck on 23 slam championships since reigning supreme at Melbourne Park in 2017, Williams was hoping to move within a step of matching Margaret Court's record.

But the 39-year-old former world number one was taken down by three-time major champion Osaka in a blockbuster battle of the big hitters on Thursday.

Japanese star Osaka will now face either Jennifer Brady or Karolina Muchova in Saturday's final as she eyes her second Australian Open crown.

Osaka – the youngest player remaining in the draw – initially struggled under the beaming Melbourne sun as fans returned to Rod Laver Arena following a five-day state-wide lockdown after a coronavirus outbreak.

She was in all sorts, struggling on serve and tallying five unforced errors through two forgettable games as Williams raced out to a 2-0 lead.

Osaka – boasting a 3-0 record in grand slam semis – faced a 30-40 deficit and potential 0-3 hole before digging deep to hold for the first time.

It proved to be a turning point for Osaka, who went on a roll by reeling off five successive games and six of the next seven to take complete control.

The tables turned on Williams, who saw her unforced-error count balloon out to 16 while only hitting four winners in the opening set.

Williams – the oldest woman to reach the semis in Melbourne in the Open Era – carried a flawless Australian Open semi-final record into the contest, having won all eight of her previous final-four showdowns.

But Williams cut a frustrated figure at the start of the second set as she yelled at herself "make a shot" amid her demise – Osaka breaking in the first game before consolidating.

However Osaka, who has gone on to win the title each time after advancing past the round of 16 at a slam – 2018 US Open, 2019 Australian Open and 2020 US Open, lost her way when serving at 4-3 as three double faults saw her broken by Williams.

Williams, beaten by Osaka in an infamous US Open final three years ago, regifted the compliment the very next game, Osaka hitting three stunning winners to break to love before sealing her place in the women's decider.

Data slam: Osaka stays hot
She has now won 20 consecutive matches since losing while on Fed Cup duty for Japan last February. A 21st successive victory would yield a fourth slam triumph.

WINNERS/UNFORCED ERRORS
Williams – 12/24
Osaka – 20/21

ACES/DOUBLE FAULTS
Williams – 3/1
Osaka – 6/8

BREAK POINTS WON
Williams – 2/7
Osaka – 4/4

Jennifer Brady believes a two-week hard quarantine upon arriving in Australia helped her make a run to the semi-finals at Melbourne Park.

As one of the 72 Australian Open entrants that had potentially been exposed to COVID-19 on chartered flights to Melbourne, Brady was forced to stay in a hotel room for a fortnight ahead of the first grand slam of the year.

However, the 25-year-old booked her place in the final four on Wednesday by coming from behind to defeat Jessica Pegula 4-6 6-2 6-1 in an hour and 40 minutes on Rod Laver Arena.

While some players voiced their displeasure with the conditions they were faced with in self-isolation, Brady felt the period served her well.

"I was pretty much going non-stop since June of last year. I was playing World TeamTennis, then played tournaments in the US, then went over to Europe and was training in Europe till December," said Brady.

"I didn't have any weeks off. Mentally I was feeling a little bit fried, to be honest. I think I used that two weeks to kind of reset mentally and also physically, just give myself, my mind, my body a little bit of a rest.

"I would say I didn't really have high expectations on myself to do well. I came out of the quarantine, and then we were lucky enough to have a separate tournament for us who were in the hard lockdown. I was lucky to get a couple matches in there before starting here in the Australian Open."

The 22nd seed will take on Karolina Muchova in the last four, the Czech having stunned world number one Ash Barty earlier in the day. In the other half of the draw, Serena Williams will take on Naomi Osaka.

Brady hopes to get an opportunity to challenge herself against 39-year-old veteran Williams, who is chasing a record-equalling 24th major singles title.

"I think just being in the same draw as Serena is obviously... when she retires, if she retires, it's going to be something I'll be extremely grateful for. I hope I get to play her before she retires," said Brady.

"Yeah, I think she's the G.O.A.T. She's the greatest of all time and definitely will be the greatest of all time."

Brady made her first grand slam semi-final appearance at last year's US Open, when Williams and Osaka were also in the final four.

She suffered a three-set loss to Osaka on that occasion, but she is pleased to be performing on a par with the Japanese and Williams.

"I think it says a lot. They're obviously great, great tennis players, champions of the sport. To be categorised in the same group as them, I'll take that as an honour," said Brady.

"I think it's a huge achievement for me to make the semi-finals here. I look to make the finals, so we'll see."

Only Muchova stands between Brady and a first major final and fans will be able to attend after lockdown was lifted in Victoria, with a crowd of 7,477 – approximately 50 per cent capacity – allowed for each session.

Brady said of her next opponent: "She's crafty. She looks to move forward, has an all-court game. She's really athletic.

"I hope it will be a good, competitive match. Yeah, I'm looking forward to it."

Serena Williams is in the Australian Open semi-finals for the first time since she last won a grand slam title, beating Simona Halep to set up a mouthwatering clash with Naomi Osaka.

The American great gained revenge for her Wimbledon final defeat to the Romanian two seasons ago as she conjured a 6-3 6-3 win on Rod Laver Arena.

Halep dropped just four games in that stunning grass-court success in 2019, the third of four grand slam finals that Williams has lost since landing her 23rd major in Australia four years ago.

The 24th title has remained frustratingly elusive, with Williams one away from matching Margaret Court's record haul, but perhaps this is the week where that changes.

She must get past Osaka, her heir apparent as the figurehead for the women's game, but Williams showed her prowess in this match, devastatingly proving a point.

Her power won out, with 24 winners to just nine from Halep, although the 33 unforced errors from Williams showed there is room for improvement in precision.

The tone was set from the first point, Williams with a brilliant forehand service return winner on the forehand side on her way to an immediate break of serve.

Halep forced her way level but Williams raised the tempo in the sixth game and a deep forehand into the Romanian's backhand corner secured a 4-2 advantage.

Williams served out the set to love at the first opportunity but then dipped early in the second set, Halep pinching a break when the American volleyed waywardly at the net.

What proved a consistent theme was Halep's struggle to hit through her opponent, and the two-time grand slam winner could not capitalise on a 3-1 lead in that second set, dropping five successive games as the 39-year-old Williams began to turn on some vintage form.

Dismissive of the often weak Halep serve, Williams swept through to the clash with Osaka.

"I definitely think this was the best match I've played this tournament for sure," Williams said. "I had to, going up against the number two in the world. I knew I had to do better and that's what I did, so I'm excited."

Looking forward to facing Osaka, Williams said in her on-court interview: "She's such a strong player on the court and such an inspirational person off the court, which I think is really cool. I've been watching her and I'm sure she's been watching me."

Former world number one Naomi Osaka is unfazed about her record at grand slams as she eyes consistency after reaching the Australian Open semi-finals.

Osaka will face either 23-time slam champion Serena Williams or Simona Halep in the semis following Tuesday's emphatic 6-2 6-2 win over Hsieh Su-wei in Melbourne.

Three-time major winner Osaka has gone on to win the title each time she has reached the quarter-finals of a slam – beating Hsieh en route to her 2019 Australian Open triumph.

Asked about the record, Osaka told reporters: "I don't really care about the stat. Just because I've only been to four quarter-finals.

"It feels something like 20. That would be cool. But four, it's not really doing too much for me.

"I would be more impressed if I didn't lose in finals. If it says 10-0 in finals. But the fact is if I don't reach the finals, I lose in the fourth round or the third round.

"For me, I'm happy to be more consistent. I think I'm being more consistent since New York, so that's the ultimate goal for me."

Osaka – in the midst of a 19-match winning streak – overpowered veteran Hsieh on Rod Laver Arena, where the Japanese star hit 24 winners and just 14 unforced errors, while she lost just two of her 25 first-service points.

It does not get any easier for Osaka, with record-chasing Williams or two-time slam champion Halep standing in the way of a trip to Saturday's decider at Melbourne Park.

"I played both of them before I think multiple times," Osaka – confident after saving two match points against Garbine Muguruza in the last 16 – said.

"Halep, I don't really like playing her. She's someone that's really tough, someone that gets the ball back every time. For me it's definitely a mental and physical battle.

"Of course, the same goes for Serena. She's Serena, someone that I feel really intimidated when I see her on the other side of the court."

Former world number one Naomi Osaka was relentless as she dismantled Hsieh Su-wei to reach the Australian Open semi-finals 6-2 6-2.

Hsieh upstaged the likes of 2019 US Open champion Bianca Andreescu en route to the quarter-finals, but the veteran was overpowered by Japanese star Osaka in Melbourne on Tuesday.

Three-time grand slam champion Osaka dominated from the outset, especially on serve – losing just two points on her first serve, as the third seed awaits record-chasing Serena Williams or Simona Halep in the final four at Melbourne Park.

Osaka emerged from the jaws of defeat in the last 16, saving a pair of match points to claim an improbable victory against last year's runner-up Garbine Muguruza.

And Osaka was a woman on a mission in sunny and warm conditions on Rod Laver Arena, where the 23-year-old broke for an early 3-1 lead.

Hsieh – the oldest player in the Open Era to make her grand slam quarter-final debut, aged 35 – had the chance to break back immediately, but Osaka held firm after fending off a pair to consolidate.

Osaka, who has gone on to win the title each time she has reached the quarter-finals of a major – beating Hsieh en route to the 2019 Australian Open crown, had another two break points saved but she still cruised in the first set.

It was a powerful but disciplined performance from Osaka, particularly on serve as she won 100 per cent of her points on first serve (12 of 12) against a helpless Hsieh.

The second set followed a similar theme – Osaka maintaining her dominance as she raced out to a 3-0 lead.

Osaka never relinquished the break, closing out the match on Hsieh's serve, with the six-time WTA Tour champion improving to 4-0 in quarter-final matches at slams, and 2-0 at the Australian Open.

Data Slam: ​Osaka extends streak
Eyeing a second Australian Open trophy, Osaka has now won 19 consecutive matches, dating back to February last year following the Tour's resumption amid the coronavirus pandemic. She last lost while on Fed Cup duty with Japan.

WINNERS/UNFORCED ERRORS
Osaka – 24/14
Hsieh – 14/23

ACES/DOUBLE FAULTS
Osaka – 7/1
Hsieh – 0/3

BREAK POINTS WON
Osaka – 4/12
Hsieh – 0/3

Simona Halep set up a quarter-final duel with Serena Williams after showing admirable character to battle back from a set down to beat Iga Swiatek 3-6 6-1 6-4 and seal her 100th grand slam match win.

Halep and Swiatek put on a thrilling show in the night session on Sunday, as the Romanian two-time grand slam champion demonstrated her fighting spirit to come from a set down and reach the last eight.

Swiatek took charge in the first set after saving the first two break points of the contest, eventually putting herself in a commanding position as she won the 10 of the final 11 points of the set, but Halep remained focused as her 19-year-old opponent began to wobble in the second.

Halep then snuffed out any threat of a turnaround by breaking back straight after losing on her own service in the decider and she went on to set up a meeting with Williams, who had overpowered Aryna Sabalenka earlier in the day.

Naomi Osaka also advanced, though she was by no means comfortable, while Hsieh Su-wei beat Marketa Vondrousova in straight sets.

HALEP'S REVENGE

Halep's clash with Swiatek was their first since the French Open last October, when Swiatek ran out a 6-1 6-2 winner and went on to claim her maiden major title.

Revenge was on the cards at Melbourne Park and Halep got the job done impressively, showing her mettle to return from a set down.

"Well, I thought before the match that I have to be a little bit more aggressive than Paris. In Paris I have been very far back, and my ball didn't go through the court," the second seed said. "So, I thought that it's a better chance to go and hit.

"The pressure came from the way I played the last match against her. I just expected a better game from myself, which I did, and I'm really happy about that."

Halep accepts facing Williams will be an entirely different challenge, but she remains confident despite lauding the American a "legend" in her on-court interview.

"Of course it's different, she's the only one with 23 grand slams, so you cannot compare Serena with all of us, because we do not have so many grand slams," Halep added.

"But when I step on the court, it's just another opponent, and always I'm focused on myself more than I focus on who I play. We played so many times. I know what to expect. I will just try to do my game, and I will be confident."

WILLIAMS ON COURSE

All eyes are on Williams yet again, as she hopes to equal Margaret Court's record of 24 grand slam titles – and on the evidence of her latest win, she will take some stopping as she won 6-4 2-6 6-4.

Williams revealed she had to cope with a little off-court stress this week with her clothing line, and Sabalenka certainly kept the pressure up as the 22-year-old took the second set.

But Williams responded well to the seventh seed, who became the first player to take a set off the former world number one. Williams said she remained confident despite that setback.

"Like I said on the court, I just felt like even games that I lost, I was so close to winning. Not all games, but probably most of those games," she said. "I just needed to play better on the big points.  I knew that I could. I still hadn't reached my peak. I was like, 'Okay, Serena, you got this, just keep going.'"

OSAKA RELEASES HER ANGER

Osaka was in a real spot of bother against Garbine Muguruza, but saved two match points.

The 2019 champion Osaka steadied herself and felt more composed after a brief show of frustration, as she struck the ground with her racquet.

Ultimately, she emerged a 4-6 6-4 7-5 victor, and Osaka felt letting frustration get the better of her for a moment helped her cause.

"On the first match point, I was just thinking that I didn't hit a decent serve that entire game, so I should really focus on my serve," he said. "I feel like my serve stats were pretty good that set, so I was just telling myself to do better.

"Then on the second point, when the rally started, I just told myself not to push [the ball] but also don't do something crazy and make a really bad unforced error. I felt the entire match I was overthinking. There was a moment when I got angry and hit my racquet on the ground. I feel like I released a lot of the thoughts that I had. It just made me go more into instinct-based tennis."

She will face Hsieh next, the world number 71 having beaten Vondrousova – ranked 51 places higher – 6-4 6-2.

Naomi Osaka and Garbine Muguruza set up a blockbuster clash at the Australian Open, while Aryna Sabalenka cannot wait to face Serena Williams.

As Williams was tested before winning through, Osaka and Muguruza raced through their third-round outings in Melbourne on Friday.

Osaka and Muguruza dropped just seven games between them to set up what will be their first meeting, which will take place without fans in attendance as Victoria prepares to move into a five-day lockdown beginning on Saturday due to coronavirus concerns.

Sabalenka also progressed and will next face Williams, while Simona Halep cruised through.

OSAKA, MUGURUZA STORM THROUGH

Osaka, the three-time grand slam champion, brushed past fellow seed Ons Jabeur 6-3 6-2 in the third round.

The Japanese star, winner of the Australian Open in 2019, is looking forward to facing fellow major champion Muguruza.

"I've practised with her once, but it was on grass, and I was younger. It was maybe like a couple years ago," Osaka said.

"But I just remember being really impressed by her, and for me, I've watched her win Wimbledon and win the French Open when I was younger, and I've always wanted to have the chance to play her. So for me, this is really exciting."

A finalist at the Yarra Valley Classic last week, Muguruza's strong start to the Australian Open continued with a 6-1 6-1 thrashing of Zarina Diyas.

"I don't think we've played each other before. Just looking forward for a fourth round, a good fourth round, playing the top players," Muguruza – who has lost just 10 games in the first three rounds – said ahead of facing Osaka. "I feel like that's always the right way, you know, a good sign. Just expecting a good match."

JOB DONE FOR SERENA

Williams' bid for a record-equalling 24th grand slam singles title remains on track after overcoming Russian teenager Anastasia Potapova 7-6 (7-5) 6-2.

In her 101st Australian Open match, Williams secured her 90th career victory in Melbourne. The 39-year-old also improved her overall slam record to 360-51 – Martina Navratilova (306-49) is the only other player to pass 300 wins in the Open Era.

Next up for Williams is Sabalenka, who was too good for Ann Li, winning 6-3 6-1 to reach a major fourth round for just the second time in her career and first in Melbourne.

The Belarusian seventh seed is not daunted by the task facing her when she meets the American for the first time.

"I want to get this thrill. Can I say thrill? I said it right. So it's going to be a thrill. But, yeah. I'm going to do everything I can," Sabalenka said.

HALEP THROUGH AS SEEDS CRUISE

Halep reached the fourth round in Melbourne for the sixth time with a convincing 6-1 6-3 win over Russian 32nd seed Veronika Kudermetova.

Awaiting the two-time major winner in the fourth round is Iga Swiatek after the Polish 15th seed got past Fiona Ferro 6-4 6-3.

Swiatek thrashed Halep 6-1 6-2 on her way to the French Open title last year.

Marketa Vondrousova, the 2019 French Open runner-up, reached the fourth round of the Australian Open for the first time after beating Sorana Cirstea 6-2 6-4.

Up next for the Czech 19th seed is Hsieh Su-wei, who battled past Sara Errani 6-4 2-6 7-5 after two hours and 44 minutes.

Errani had won her previous three meetings with Hsieh in straight sets, including winning a set 6-0 - known as a 'bagel' in tennis parlance - in each of those victories.

It meant Hsieh, 35, had a simple plan against the Italian.

"I don't remember when I lose to someone but someone reminded me I eat the bagel every time so I said, 'Okay, I will try to not take any bagel today'," she said.

Naomi Osaka admitted it was "a bit funny" to be deemed an essential worker as the Australian Open goes on.

The year's first grand slam is set to continue without fans from Saturday as Victoria heads into a five-day lockdown amid coronavirus concerns.

Professional athletes have been deemed "essential workers", meaning the Australian Open can continue.

Osaka, who raced into the fourth round with a 6-3 6-2 victory over Ons Jabeur on Friday, said that seemed strange.

Asked how she felt about being described as an essential worker, the Japanese star told a news conference: "Well, I'm not really sure.

"That kind of seems a bit funny. But I don't know, I don't make the rules. I'm just here just trying to have fun."

Three-time grand slam champion Osaka will face Garbine Muguruza in a blockbuster fourth-round clash.

Serena Williams and Naomi Osaka sizzled in the scorching Melbourne heat on day three of the Australian Open. 

Williams, aiming once more for a record-equalling 24th singles grand slam, made serene progress from round two on what was the hottest day of the tournament so far. 

It was a similar story for Osaka, who is aiming to become a two-time champion at Melbourne Park, but Simona Halep had to dig deep while Bianca Andreescu and Petra Kvitova were early casualties on Wednesday.

PLAIN SAILING FOR SERENA AND OSAKA

Williams' perfect start to the season extended to 5-0 as she swatted aside Nina Stojanovic 6-3 6-0 to set up a round-three meeting with Anastasia Potapova – the same opponent she overcame in Melbourne in the first round a year ago. 

The seven-time Australian Open champion is looking forward to renewing acquaintances with the Russian. 

"It's always a fun, interesting match [against Potapova]. I'm gonna go home, get ready and just do the best," she said.  

"We're all out here to have fun and I'm happy to be out here, and just to be playing in front of crowd again is really cool. So every day is just fun." 

Osaka, the current US Open champion and the winner in Melbourne two years ago, hammered former world number four Caroline Garcia 6-2 6-3 on Rod Laver Arena in the evening session. 

The Japanese star is set to face her friend Ons Jabeur for the first time in an official match in round three. 

"She's really funny," Osaka said of her next opponent. "I don't know if you guys watch any of her interviews. I think she is really funny and nice.  

"I think the match I am going to play against her will be really difficult, but I'm looking forward to it." 

HALEP SURVIVES TOMLJANOVIC TEST

In contrast to Williams and Osaka's comfortable wins, second seed Halep was taken to the brink by home favourite Ajla Tomljanovic, who won the first set and was serving for the match in the third. 

However, 2018 finalist Halep broke back when trailing 5-4 in the decider and battled through with a 4-6 6-4 7-5 victory in a match that saw a combined 94 unforced errors (57 for Tomljanovic, 37 for Halep). 

"I was expecting that she would play very hard and very strong. I expected it to be a difficult match, but it was more than I thought. But I'm really happy that I can smile now," Halep said.  

"I was not that positive when I was talking to myself. I didn't talk about the score, I was just blaming myself, that I'm not strong enough to win against her. But in the end mentally I was maybe a bit stronger than her, and I didn't want to give up." 

Last year's losing finalist Garbine Muguruza (14) was too good for Ludmilla Samsonova in a 6-3 6-1 win, while French Open champion Iga Swiatek (15) dispatched Camila Giorgi 6-2 6-4. 

Aryna Sabalenka (7), Marketa Vondrousova (19) and Veronika Kudermetova (32) all made it through, but fellow seed Elena Rybakina (17) was beaten in straight sets by Fiona Ferro.

EARLY EXITS FOR ANDREESCU AND KVITOVA

Andreescu became the latest scalp for veteran Hsieh Su-Wei, who earned a commanding 6-3 6-2 victory and is now 4-3 against top-10 players in the slams since 2017. 

Eighth seed Andreescu won the US Open in 2019 but missed the entirety of last year with a knee injury, while her preparation here was disrupted by spending 14 days in quarantine after her coach tested positive for coronavirus. 

"After my first round, I thought I would feel more exhausted, but I felt amazing. Also, today the weather was a bit tricky. Being in the heart of quarantine I could have had those extra two weeks of like being in the heat and getting used to sweating and all of that," she said. 

Next up for Hsieh is Sara Errani, who defeated Venus Williams 6-1 6-0. The veteran American rolled her ankle towards the end of the first set and, despite needing two medical timeouts, valiantly saw out the match. 

Kvitova was a runner-up to Osaka in 2019 and appeared on course to recovery after dominating the second set against Sorana Cirstea. 

But amid sweltering conditions, the Czech ninth seed went on to lose the decider. 

"It was quite a rollercoaster, for sure," she said. "Unfortunately I couldn't take the chances to win the first set.  

"I think that was really the key of the match. She really had a great day today; she played a good game. I didn't really bring the best tennis today. It's really hurting."

Garbine Muguruza continued her impressive form to book a meeting with Ash Barty in the Yarra Valley Classic final.

Muguruza, the Spanish sixth seed at the WTA 500 event, crushed Marketa Vondrousova 6-1 6-0 on Saturday.

The two-time grand slam champion has lost just 10 games in four matches on her way to the final.

Muguruza lost just eight points on serve against Vondrousova while converting five of 11 break points.

She will meet Barty in the final after the Australian benefited from Serena Williams' withdrawal as the 23-time grand slam winner deals with a shoulder injury.

Naomi Osaka and Victoria Azarenka also withdrew on Saturday from the Gippsland Trophy and Grampians Trophy respectively.

At the Grampians Trophy, Anett Kontaveit was given a passage into the semi-finals, where Maria Sakkari awaits after her 6-4 6-2 win over Angelique Kerber.

Jennifer Brady and Ann Li will meet in the other semi after wins over Barbora Krejcikova and Sorana Cirstea respectively.

Elise Mertens will play the Gippsland Trophy final after Osaka's withdrawal with the Belgian to face Kaia Kanepi, who overcame Ekaterina Alexandrova 6-3 7-6 (8-6) to reach her first WTA decider since 2013.

Naomi Osaka said the scheduling of lead-up events was a factor in her decision to withdraw from the Gippsland Trophy on Saturday.

The three-time major champion opted to pull out of her scheduled semi-final against Elise Mertens due to a shoulder injury.

Osaka, 23, was due to play a fourth match in five days, but decided to withdraw ahead of the Australian Open starting on Monday.

"Anyone that's kind of followed me for a bit knows that I've kind of had a slight shoulder thing since like 2018 in Beijing," the Japanese star told a news conference.

"It kind of flared up again because I played a lot of matches back-to-back. But, for me, my main focus is hoping I can rest enough before the Open."

Osaka, who will face Anastasia Pavlyuchenkova in the Australian Open first round, said the time between the Gippsland Trophy and year's first major also impacted her decision.

"I would say it is a factor because for me, I don't normally play the tournament right before a slam," she said.

"But I felt like it was really necessary to get matches in. I think everyone felt that way.

"I'm kind of sad that I wasn't able to play today. But I think in the end it's the right decision."

Naomi Osaka and Victoria Azarenka withdrew from their respective tournaments on Saturday due to injuries.

Osaka, a three-time grand slam champion, opted out of her Gippsland Trophy semi-final against Elise Mertens.

Azarenka, meanwhile, was due to face Anett Kontaveit in the Grampians Trophy quarter-finals.

Osaka said her move was a cautious one ahead of the Australian Open, which begins on Monday.

"Sorry to Tennis Australia and the fans to have to withdraw today," she said, via the WTA.

"I have a niggling injury and in light of the Australian Open on the horizon, I need to be cautious. I look forward to competing next week."

It continues what has been a difficult build-up to the first grand slam of the year.

On Friday, Serena Williams withdrew from her semi-final at the Yarra Valley Classic due to a right shoulder injury.

It comes amid a busy schedule for players after Thursday's action was called off due to a coronavirus scare.

One in eight women in the Australian Open draw have already won a grand slam title.

One in eight. It is staggering that of the 128 players who set out in the hope of singles glory at Melbourne Park, there are 16 major champions among them, and perhaps never has it been so difficult to predict who will carry off the title.

Compare it to the men's draw, where there are just five grand slam singles winners, and where you would struggle to make a compelling case for any more than three of those this year, with apologies to Stan Wawrinka and Marin Cilic.

As long-running dynasties near their end on the men's and women's tours, the WTA is a lengthy step ahead of the ATP with a cast of appealing characters already assuming leading roles.

The leader of the pack

Three-time grand slam champion Naomi Osaka is at the forefront of a school of rising stars, but she has impressive rivals for company.

The last four years have seen the 15 women's majors won by 12 different players, whereas in the men's game, Rafael Nadal (6), Novak Djokovic (5), Roger Federer (3) and Dominic Thiem (1) have creamed off all the top prizes in the same period.

Often criticised in the past for a perceived lack of depth, in the years when Serena Williams won seemingly at will, the women's tour has exploded with a rush of bright and young talent.

Osaka is a revelation and a leader, on and off the court. Twice a US Open champion now, and a winner in Australia two years ago, the 23-year-old Japanese star took a powerful stance for racial equality at Flushing Meadows back in September, at the height of Black Lives Matter protests. She wants to achieve even more off the court than on it, where she looks assured of one day leaving an impressive legacy.

If there is any area where Osaka's game falls down it is consistency. She has surprisingly not passed the fourth round in 14 of her 17 grand slam appearances, but on every occasion she has gone beyond that stage it has been en route to lifting a trophy.

In hot pursuit

Last year's three slam champions were, at the times of their triumphs, just 21 (Sofia Kenin - Australian Open), 19 (Iga Swiatek - French Open) and 22 (Osaka - US Open).

The women's game has not seen anything comparable in terms of youthful winners of its blue riband tournaments since 2004, when the 21-year-old Justine Henin won in Australia, Anastasia Myskina landed the Roland Garros title at 22, Maria Sharapova was a 17-year-old bolter to Wimbledon glory and 19-year-old Svetlana Kuznetsova scored a stunning Flushing Meadows victory.

Last year does not touch the 1997 season, when a 16-year-old Martina Hingis won the Australian Open, Wimbledon and US Open, denied a grand slam clean sweep by 19-year-old Iva Majoli's shock French Open final win over the Swiss.

But women's tennis is still seeing a remarkable shift to relative youth.

The 2019 season saw a then 19-year-old Bianca Andreescu scoop a stunning US Open win, while Ash Barty took the French Open.

Andreescu has been sidelined with a knee injury since the 2019 WTA Finals, but she is back for Australia, where Queenslander Barty, now 24, is the home hero.

Brace for the prospect of Andreescu and Barty joining Kenin, Swiatek and Osaka in a group of five who can take the women's game boldly into the post-Williams era.

But the Williams era isn't over

This is true, and again Serena will make another attempt to land that elusive 24th grand slam, the one that would move her level with Margaret Court on the all-time list.

She remains, at the age of 39, a magnificent competitor and a beguiling player, as does sister Venus, who turns 41 in June.

Serena has lost her last four grand slam finals, however, and the most recent run to a title match came almost 18 months ago in New York, where Andreescu had her number.

As the new gang of five threaten to pull away from the old establishment, perhaps Williams is now in the next group, along with the likes of Simona Halep, Victoria Azarenka and Petra Kvitova: still perfectly capable of winning another slam or even multiple slams, but it feels important to strike now.

Serena has not won any of her last 10 slams, making it the longest span in her professional career without winning a major.

Barty party, or Sofia the second?

Osaka begins the Australian Open as favourite with bookmakers, but world number one Barty will have home support and could make that count. How she performs will be keenly watched, given she chose not to travel once the COVID-19 pandemic hit last year, sitting out 11 months.

Should Barty get on a roll, hopes will be high she can become the first Australian woman to take the title since Chris O'Neil in 1978. Last year, Barty fell in the semi-finals to Kenin, and she will be eager to land a second slam title.

Kenin, whose intense concentration and steely resolve helped her pull off last year's shock Melbourne win, and follow up with a run to the French Open final, can be a match for anyone. She will be aiming to become the first woman to win back-to-back Australian Open titles since Azarenka in 2012 and 2013.

Success on this level has come perhaps ahead of schedule for the American, and the same can be said for Swiatek, whose demolition of the field at Roland Garros in October made a mockery of her being ranked number 53 in the world.

The teenage Polish player became her country's first grand slam singles champion, and with that status comes the expectation she will follow it up. How that turns out for her will be one of the most intriguing of sub-plots in the new season.

Changing priorities

Halep said in a recent WTA interview that winning an Olympic medal was her "main goal" for 2021, although Osaka will also have the Tokyo Games firmly circled in her diary.

For the likes of those other players among the 16 slam winners in the Melbourne draw, there will be differing targets this year, too.

Angelique Kerber, Sloane Stephens, Jelena Ostapenko and particularly Garbine Muguruza may yet come good again on the big stage at some point this season.

For Venus Williams, Kuznetsova and Samantha Stosur, it may be a case of one final hurrah.

As the likes of Coco Gauff emerge as potential future big-stage winners, and fledgling ambassadors, the women's game looks in safe hands.

Serena Williams roared into the quarter-finals of the Yarra Valley Classic with a 6-1 6-4 victory over Tsvetana Pironkova on a star-studded day of action in Australia.

The 23-time grand slam champion was in fine form at Melbourne Park, where the biggest names in women's tennis were competing across multiple tournaments, as she sealed a straight-sets triumph to continue her preparations for a shot at an eighth Australian Open title.

In doing so the 39-year-old extended her head-to-head record over the Bulgarian to 6-0 and was delighted to get the job done.

"It's definitely nice to get another win," the American said during her on-court interview.

"She's clearly a great player, so it wasn't easy, but it was good to come through."

Speaking at her media conference, Williams added: "Last time it was an incredible three-set match, so today I was like, 'All right, let's really try and focus and learn to do better than last time.'"

World number one Ash Barty had a less straightforward path to the last eight, requiring three sets to see off Marie Bouzkova.

The home hope ultimately prevailed 6-0 4-6 6-3, with second seed and reigning Australian Open champion Sofia Kenin also taken the distance in a 5-7 7-5 6-2 win over Jessica Pegula, as Nadia Podoroska dug deep to down Petra Kvitova 5-7 6-1 7-6 (9-7).

With Barty now set to face Shelby Rogers, Danielle Collins awaits Williams having impressively defeated third seed Karolina Pliskova 7-6 (7-5) 7-6 (7-3), while Garbine Muguruza overcame Anastasia Pavlyuchenkova 6-1 6-2 to set up a meeting with Kenin.

In the Gippsland Trophy, the top three seeds all dodged upsets, with two-time grand slam winner Simona Halep, 2019 Australian Open victor Naomi Osaka and 2018 Tour Finals champion Elina Svitolina safely navigating through the last 16.

Fifth-seeded Briton Johanna Konta failed to convert two match points as she succumbed to a 4-6 7-6 (12-10) 7-6 (7-4) defeat to Irina-Camelia Begu.

Meanwhile, at the Grampians Trophy there were wins for Anett Kontaveit, Jennifer Brady and Angelique Kerber.