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."

Serena Williams admitted she would be dealing with her shoulder injury during the Australian Open, but the star is "very confident" she will be ready to go.

Williams withdrew from the Yarra Valley Classic on Friday due to a right shoulder injury.

Asked how she was feeling on Saturday, the 23-time grand slam singles champion was upbeat.

"I feel pretty good. I've gotten a lot of treatment already on my shoulder.  But I'm super confident it's going to be great," Williams told a news conference.

"I'm feeling very confident, I think is a better word, and getting ready for hopefully the next two weeks."

However, Williams said the injury would be an issue throughout the Australian Open, which begins on Monday.

"It's definitely something that I'm going to have to deal with for the fortnight. Kind of knowing that going into a tournament definitely helps," the 39-year-old said.

"Also knowing, okay, I'm going to have to probably pick up some different therapy exercises after each match, etcetera.

"It's going to be really important."

Williams' last grand slam title came in Melbourne in 2017 and all eyes will again be on the American in her bid to equal Margaret Court's record of 24 major crowns.

While that record is again on her mind, Williams – who will face Laura Siegemund in the first round – said she was now more relaxed about it.

"It's definitely on my shoulders and on my mind. I think it's good to be on my mind," she said.

"I think it's a different burden, I should say, on my shoulders because I'm used to it now. It's more relaxing I would like to say, yeah."

Sofia Kenin insisted her leg injury was improving as she prepares for her Australian Open title defence.

In a rematch of last year's Australian Open decider, Kenin was crushed 6-2 6-2 by Garbine Muguruza in the Yarra Valley Classic quarter-finals on Friday.

Kenin, 22, said she struggled with a leg injury which she hopes will not affect her at Melbourne Park, where the year's first grand slam begins on Monday.

"It was my left groin and my left glute, it was completely sore," the American told a news conference on Saturday.

"I think I was rolling a lot yesterday. Even before the match I rolled probably like an hour before they even finished. I was just rolling with the Theragun. It kind of got better, but it wasn't the best. She obviously played well."

Kenin, who will face Maddison Inglis in the Australian Open first round, added: "It's better, which I don't understand. From a match, now today it's better. Thank God. Obviously I'm not going to complain about that. I want it to be better for AO."

The defending champion's injury worry is just the latest ahead of the Australian Open, with Serena Williams, Naomi Osaka and Victoria Azarenka among those withdrawing from lead-up tournaments.

Kenin believes quarantine ahead of events had an impact, as well as long lay-offs.

"People who haven't played matches for two weeks, it's obviously not the same. Everyone is using this tournament to prepare for Australian Open," she said.

"Obviously you can see that being in a room for two weeks, not playing, practising, it's not the same as playing a match clearly. After two matches, my leg is completely sore. 

"Yeah, it's obviously different. But everyone's obviously going to be ready for Australian Open, for sure."

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.

Novak Djokovic said it was "a tough one" to take after Serbia's hopes of retaining the ATP Cup title were ended by defeat to Germany.

The world number one scored a tense 6-7 (3-7) 6-2 7-5 victory over Alexander Zverev in their singles rubber, levelling the match after Jan-Lennard Struff beat Dusan Lajovic in three sets.

Zverev and Struff then teamed up in doubles to net a 7-6 (7-4) 5-7 10-7 win over Djokovic and Nikola Cacic.

The singles workout and win sets up the eight-time Australian Open champion well for the start of that grand slam next week, which was the consolation Djokovic could take from defeat.

Speaking about his singles clash with Zverev, Djokovic said: "It was anybody's game really. He was a set up, a couple points here and there in the beginning of the second. I just returned well when I needed to and closed out the match.

"It's never easy playing against Sascha [Zverev] when he's in form, and he's in really good form. We pushed each other to the very limit, and I'm glad that I had such a battle with him.

"It's unfortunate we lost the tie. That's what this competition is all about. It's about the team, not about winning one match, a singles match. Yeah, it's a tough one."

Germany advance to face Russia in the semi-finals on Saturday, with Daniil Medvedev and Andrey Rublev a formidable combination awaiting them.

Spain secured a shot at Italy in the second semi-final, despite a 2-1 defeat to Greece on Friday.

The Spanish team needed just one win in the group-stage match to advance, and that predictably came as Pablo Carreno Busta, ranked 16th by the ATP, beat world number 462 Michail Pervolarakis.

His 6-3 6-4 success could not be matched by team-mate Roberto Bautista Agut, who fell to a 7-5 7-5 defeat against Stefanos Tsitsipas, while Spain retired from the doubles rubber after one game, giving Greece a 2-1 success in the tie.

It remains to be seen whether Rafael Nadal will be fit to play any part in the semi-final, with the 20-time grand slam champion having been absent so far in the campaign due to a back injury.

"He's working very hard to recover his best feelings," said Spain captain Pepe Vendrell.

"Obviously he couldn't play any matches during the week. It's a situation that we have to study. But day by day he's improving. We will see [on Saturday] if he can play."

AWAY FROM THE ATP CUP, WAWRINKA ABANDONS

In the Murray River Open, Stan Wawrinka withdrew from his quarter-final with Jeremy Chardy after beating Australian Alex Bolt in a tough three-set match earlier in the day. Corentin Moutet, Dan Evans and Felix Auger-Aliassime joined Chardy in the last-four line-up.

Evans defeated Borna Coric, who had eliminated Australian hope Nick Kyrgios in his previous match.

All ATP and WTA tournaments are being played at Melbourne Park this week.

Thursday's play was cancelled due to a COVID-19 case affecting a worker from a hotel that accommodated quarantining players, and that meant Friday's schedule was packed.

The Great Ocean Road Open also saw players needing to win two matches in a day to reach the semi-finals, with Karen Khachanov, Thiago Monteiro and the Italian pair of Jannik Sinner and Stefano Travaglia coming through.

Serena Williams has withdrawn from her semi-final at the Yarra Valley Classic due to an injury to her right shoulder.

As a result, home favourite Ash Barty will progress to the final of the Australian Open warm-up event at Melbourne Park.

Williams, who is chasing an eighth Australian Open crown and an historic 24th grand slam singles success, had been in impressive form this week, demolishing Tsvetana Pironkova in straight sets.

Friday's quarter-final against American Danielle Collins proved a harder slog, as she was forced into a match tiebreak to win 6-2 4-6 10-6.

An anticipated showdown against Barty will now not come to pass, with the world number one to pursue a ninth career title against either Garbine Muguruza or Marketa Vondrousova.

"I think the rust is always there for everyone the first few matches of the season. But without a doubt, I felt better and better each match," Barty told reporters after being taken the distance by Shelby Rodgers.

"Each match has been very different, different challenges, different things I've had to overcome, which is the best thing, to be able to work through those and give myself another chance to play a little bit better the next day, focus on some new challenges for the next day."

Williams is due to face Germany's Laura Siegemund in the first round of the Australian Open on Monday.

Australian Open champion Novak Djokovic could face Dominic Thiem in a mouth-watering semi-final after being handed a tough path to success at Melbourne Park, where Serena Williams will continue her quest for a 24th grand slam singles title.

The Australian Open draw took place on Friday, with world number one Djokovic set to play Frenchman Jeremy Chardy in the opening round of the year's first major tournament.

Amid coronavirus concerns in Melbourne, where Swiss great Roger Federer is absent, Djokovic has set his sights on a ninth crown and 18th major success, but the top seed's title defence is far from straightforward.

Djokovic could face Gael Monfils (fourth round) and sixth seed Alexander Zverev (quarter-final) en route to a possible semi-final against US Open champion and third seed Thiem.

The Serb overcame Thiem in a five-set thriller in last year's Australian Open final, before the latter broke through for his maiden major trophy at Flushing Meadows.

Djokovic could then meet second seed and 20-time major champion Rafael Nadal in a blockbuster final – he blitzed the Spanish superstar in the 2019 Australian Open decider but lost in three one-sided sets in their previous meeting in the French Open final.

Nadal will go head-to-head with another Serb in the first round – Laslo Djere – while Stefanos Tsitsipas could await in the quarters, with 2019 US Open final opponent Daniil Medvedev also on the same side of the draw.

Meanwhile, Williams' bid for a record-equalling 24th slam will begin against German Laura Siegemund.

The 39-year-old Williams has been stuck on 23 majors since winning the Australian Open in 2017 – losing finals at Wimbledon (2018 and 2019) and the US Open (2018 and 2019).

World number one and local hope Ashleigh Barty will meet Montenegro's Danka Kovinic in round one and defending champion Sofia Kenin faces Australian wildcard Maddison Inglis.

The last 16 could see Williams clash with Aryna Sabalenka, Barty meet Petra Martic, Kenin tackle Johanna Konta and three-time major champion Naomi Osaka do battle with last year's runner-up Garbine Muguruza.

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.

Australian Open tournament director Craig Tiley said there were no plans to change the schedule for the major amid coronavirus concerns.

More than 500 players and officials were forced into isolation after a worker at an Australian Open quarantine hotel tested positive for COVID-19.

It led to play at lead-up events in Melbourne on Thursday being called off and sparked fears around the year's first grand slam, which is scheduled to begin on Monday.

But Tiley is hoping play is back underway on Friday and said he expects the Australian Open to start as scheduled.

"The intention is to start the Australian Open on Monday so there's no intention of changing the time for the Australian Open," he told a news conference.

Tiley added: "We're absolutely confident the Australian Open is going to go ahead.

"We know that we've got a period now that we've got to work through with those 507 players and their staff, 160 players actually, that need a test and we fully expect the probability is very low that there's going to be any issue.

"We fully expect them all to test negative and then we continue with play tomorrow like we originally planned and if we have to go through this again we'll continue to go through this again and we've got another three and a half weeks of tennis, we've got a lot of tennis to play and fully expect to keep the original schedule once we get past today."

The draw for the Australian Open was pushed back to Friday, while crowds are still expected to be in attendance for the major.

Preparations for the Australian Open were dealt a fresh blow on Wednesday when a member of hotel staff tested positive for coronavirus, although Victoria's premier insists the tournament is not under threat at this stage.

A 26-year-old worker at the Grand Hyatt Hotel returned a negative test at the end of his previous shift on January 29 but subsequently developed symptoms and tested positive on Wednesday.

As a result, Melbourne and the wider Victoria region has reverted to its New Year's Eve restrictions of gatherings at home being limited to 15 people and masks having to be worn in public indoor spaces.

In terms of the specific impact upon participants in the Australian Open, players, officials and support staff who were staying at the hotel during this period must now isolate and undertake a COVID-19 test.

The number of tournament-related personnel classed as "casual contacts" related to the incident is estimated to be between 500 and 600.

Nevertheless, Victorian premier Daniel Andrews told a news conference he was confident the Australian Open would go ahead as planned, even though the requirement that some players isolate and test could have an impact upon warm-up tournaments that are ongoing at Melbourne Park.

"There's about 500-600 people that are either players and officials and others who are casual contacts," Andrews said.

"They will be isolating until they get a negative test and that work will be done tomorrow so it might have an impact on tomorrow's play in the lead-up event, but at this stage there's no impact to the tournament proper.

"That's important to us, but the issue we're most focused on is much broader. That's about public health and public safety and that's why we've really pounced on this."

The Australian Open is scheduled to run from February 8-21.

Daniil Medvedev and Andrey Rublev produced ruthless performances as Russia cruised into the ATP Cup semi-finals.

Russia followed up their day-one win over Argentina with victory against Japan to ensure they will finish top of Group D.

Rublev got things rolling with an emphatic 6-1 6-3 win over Yoshihito Nishioka and Medvedev dispatched Kei Nishikori in a 6-2 6-4 triumph.

Those results meant the subsequent doubles match – which Japan won – would not be relevant.

"I am really happy for the team," said ATP Finals champion Medvedev, who has now won 12 matches in a row on the tour.

"Reaching the semi-finals is a big step – I am really happy that we made it in both singles. Both matches were straight sets, so really happy for the team and hopefully we can go further than that."

Italy, who had beaten Austria on the opening day, are also through after Fabio Fognini and Matteo Berrettini earned wins in straight sets over France duo Benoit Paire and Gael Monfils on Wednesday.

France play Austria next but neither team can catch Italy in Group C.

Alexander Zverev won a thriller against Denis Shapovalov 6-7 (5-7) 6-3 7-6 (7-4) to ensure Germany defeated Canada.

It was a first win at the ATP Cup for US Open runner up Zverev, who had a miserable tournament in 2020.

That sets up a day three contest for Germany against Novak Djokovic and Serbia where the winning team will progress to face Russia.

KYRGIOS AND WAWRINKA THROUGH

Nick Kyrgios – playing his first tournament for a year – made it two wins from two at the Murray River Open, defeating fellow Australian Harry Bourchier 6-2 7-6 (9-7).

First seed Stan Wawrinka survived a scare before prevailing against Mikhail Kukushkin to win 4-6 6-3 6-1 in just under two hours.

Wawrinka will take on Alex Bolt in the last 16, while Kyrgios should be tested against fourth seed Borna Coric.

At the Great Ocean Road Open, top seed David Goffin crashed out as world number 146 Carlos Alcaraz celebrated a shock 6-3 6-3 victory.

Karen Khachanov and Jannik Sinner were among the seeds who progressed, both winning without dropping a set.

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.

World number one Ash Barty won her first WTA Tour match in almost a year at the Yarra Valley Classic, while Naomi Osaka got her Gippsland Trophy campaign going with a victory.

Barty sat out the vast majority of the 2020 season due to the coronavirus pandemic but marked her comeback with a 6-3 6-3 success over Ana Bogdan at Melbourne Park.

The Australian will face Marie Bouzkova next after the Czech defeated Aliona Bolsova on Tuesday.

Garbine Muguruza raced past Alison Van Uytvanck 6-2 6-0 and she was joined in the third round by Petra Kvitova, who battled to beat Venus Williams 7-6 (8-6) 7-5.

Reigning Australian Open champion Sofia Kenin, who was 7-5 up when Camila Giorgi retired from their match, is also through.

In her first match since winning the US Open in September, Osaka cruised to a 6-2 6-2 success against Alize Cornet and will meet Katie Boulter after the Briton came from a set down to beat Coco Gauff 3-6 7-5 6-2.

Iga Swiatek was also making her first appearance since winning a major title – the French Open last October – and after a slow start won 10 of the final 11 games to beat Kaja Juvan 2-6 6-2 6-1.

Aryna Sabalenka ended 2020 with back-to-back titles in Ostrava and Linz, before kicking off the new year with another trophy in Abu Dhabi. However, her run of 15 straight victories ended with a 1-6 6-2 1-6 loss to Kaia Kanepi.

Bianca Andreescu was due to gear up for the Australian Open by contesting the Grampians Trophy this week but withdrew from the competition to focus on training instead.