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."

Daniil Medvedev secured his first Australian Open semi-final berth after continuing his domination of fellow Russian Andrey Rublev in straight sets.

Medvedev starred in the Melbourne heat as countryman Rublev faded, winning 7-5 6-3 6-2 on Wednesday to reach his third grand slam semi-final, equalling Alex Metreveli for third place on the Open Era list for most major semis by a Russian man.

World number four Medvedev – the fifth Russian man to reach the Australian Open semis in the Open Era, after Metreveli (1972), Yevgeny Kafelnikov (1999-2000), Marat Safin (2002, 2004-05) and Aslan Karatsev (2021) – will face either 20-time slam champion Rafael Nadal or Stefanos Tsitsipas for a spot in the decider.

Medvedev and Rublev were meeting for the fourth time on the ATP Tour – their second in a grand slam quarter-final, with the former winning all previous meetings in straight sets. 

Runner-up at the 2019 US Open, Medvedev had a glimpse on Rublev's serve before breaking in the sixth game for a 4-2 lead, only to hand the break straight back to his countryman.

The tense battle continued behind closed doors on Rod Laver Arena as a tie-break loomed large, until Medvedev closed out the 46-minute set on Rublev's serve.

It was a similar theme in the second set, with little separating the two Russian hopefuls under the warm Melbourne sun.

Rublev, who won five ATP Tour titles last year – more than any other player, while earning a joint-best 41 wins in 2020 alongside world number one Novak Djokovic, continued to take the match to Medvedev.

Three break-point chances came Rublev's way in the seventh game, but he was unable to convert and Medvedev made him pay as the world number four broke the very next game before earning a two-sets-to-love lead.

Rublev – eyeing his first slam semi – deteriorated in the warm conditions, often hunched over between points while trying to keep cool in the shade, as Medvedev cruised.

Data Slam: Medvedev extends streak
There is no stopping Medvedev at the moment after he extended his winning streak to 19 matches, already a career-best run – dating back to the Vienna Open last October.

WINNERS/UNFORCED ERRORS
Medvedev – 30/33
Rublev – 20/39

ACES/DOUBLE FAULTS
Medvedev – 14/4
Rublev – 8/3

BREAK POINTS WON
Medvedev – 5/11
Rublev – 1/5

LeBron James' double-double fired the Los Angeles Lakers back to winning ways, while James Harden stepped up to rally the Kyrie Irving-less Brooklyn Nets past the high-flying Phoenix Suns.

James put up 30 points, 13 rebounds and seven assists as the reigning NBA champions leaned on their defense in the 112-104 victory over the last-placed Minnesota Timberwolves.

Without the injured Anthony Davis, Dennis Schroder played the supporting role for James, posting 24 points, while the Lakers battled to claim eight steals and seven blocks in a closely fought contest.

After taking a two-point lead into the fourth quarter at Target Center, the road side pulled away in the closing stages to improve to 22-7 in second place in the Western Conference.

Harden pulled out the stops with a double-double to lead the Nets to a sensational 128-124 comeback win against the Suns, despite playing without Irving after the star guard felt tightness in his lower back.

Nets coach Steve Nash revealed Irving received treatment at half-time of Brooklyn's win against the Sacramento Kings on Monday but expects the six-time All-Star to only be sidelined in the short term.

The Nets surged, scoring 40 fourth-quarter points to turn around a 24-point deficit, with Harden (38 points, 11 assists and seven rebounds) backed up by Joe Harris (22 points) as they halted the Suns' six-game winning streak.

Jokic burns Celtics but Nuggets fall short, Zion on target for Pelicans

Nikola Jokic lit up the Boston Celtics, scoring 43 points, but the Denver Nuggets could still not make triple-digits as their three-game winning stretch was ended in a 112-99 loss.

Zion Williamson shot an efficient 31 points, sinking 13 of his 16 field-goal efforts and going four-of-four from the free-throw line, as the New Orleans Pelicans snapped a three-match losing run with a 144-113 win over the Memphis Grizzlies.

Meanwhile, Damian Lillard’s 31-point, 10-assist double-double led the Portland Trail Blazers past the Oklahoma City Thunder in a 115-104 win, while centre Enes Kanter pulled down 21 rebounds.

Bazley struggles to take his chances

The Thunder never recovered against the Blazers after falling 34-21 behind in the first quarter and forward Darius Bazley was one player that could not find his range.

Bazley shot four from 16 from the field for 14 points during his 36 minutes on court, only dropping one his seven efforts from three-point range.

Giannis powers up but the Raps edge the Bucks

Giannis Antetokounmpo proved unplayable at times, scoring 34 points in the Milwaukee Bucks' 124-113 loss against the Toronto Raptors, as he ghosted past three defenders for one of his buckets.

Tuesday's results

Boston Celtics 112-99 Denver Nuggets
Portland Trail Blazers 115-104 Oklahoma City Thunder 
Los Angeles Lakers 112-104 Minnesota Timberwolves
New Orleans Pelicans 144-113 Memphis Grizzlies 
Toronto Raptors 124-113 Milwaukee Bucks 
Brooklyn Nets 128-124 Phoenix Suns

Jazz at Clippers

There has been no stopping the Utah Jazz, who have won eight straight and 19 of their past 20 games to establish a lead in the Western Conference, but a tough challenge awaits when they go on the road to face the third-placed Los Angeles Clippers on Wednesday.

Sofia Kenin revealed she had her appendix removed after being diagnosed with acute appendicitis following her shock Australian Open exit.

Australian Open champion in 2020, Kenin was dethroned in the opening week of the grand slam at Melbourne Park, where she was stunned by Kaia Kanepi in the second round last Thursday.

American star Kenin – who suffered her earliest major exit since Wimbledon in 2019 – revealed via social media on Wednesday that she had an operation in Melbourne.

"Hey guys! I want to share with you what happened to me a few days ago," Kenin said via Twitter.

"I went to the tournament physician office on Monday, February 15th with acute abdominal pain. I was evaluated by the tournament physician and referred to the hospital for further evaluation.

"Acute appendicitis was diagnosed following the completion of my CT scan. I had to have surgery and had my appendix removed on Monday, February 15, at Epworth Hospital Richmond. 

"I want to thank everyone at Epworth Hospital Richmond for taking good care of me!"

Boston Celtics star Jayson Tatum admitted he is still battling with the after-effects of coronavirus despite returning to NBA action three weeks ago.

Speaking ahead of Boston's 112-99 win over the Denver Nuggets on Tuesday, where Tatum contributed 21 points, six rebounds and eight assists, the All-Star revealed he was still experiencing respiratory issues during games.

Tatum tested positive for COVID-19 in early January, alongside some team-mates, forcing three Boston games to be postponed.

"I think it messes with your breathing a little bit," Tatum told reporters.

"I have experienced some games where, I don't want to say struggling to breathe, but you get fatigued a lot quicker than normal. Just running up and down the court a few times, it's easier to get out of breath or tired a lot faster; I've noticed that since I've had COVID.

"It's just something I'm working on. It's gotten better since the first game I played, but I still deal with it from time to time."

The Celtics have a 7-10 record since then, slipping to third in the Atlantic Division of the Eastern Conference, behind the Philadelphia 76ers and Brooklyn Nets.

After a period of quarantine, Tatum returned to the court with 24 points against the Chicago Bulls on January 25.

Tatum has not missed any of Boston's 12 matches since returning, top scoring for the Celtics on seven occasions, insisting the issues have not affected his performances or output.

"It's gotten better obviously from the first game I came back and played, but I guess it's just a long process," he said.

"I've talked to other guys that have had it and they say they experienced the same thing and it kind of just gets better over time. But as much as we play, I guess it takes a little bit longer.

"You've got to take it on the chin when things aren't going great and you're not playing how you should be."

World number one Ash Barty refused to criticise Karolina Muchova's reasoning for a medical timeout after she was surprisingly beaten in the Australian Open quarter-finals.

Barty's bid to become the first Australian woman to win the Melbourne grand slam since 1978 came to a shock end on Wednesday, upstaged by 25th seed Muchova 1-6 6-3 6-2.

Winner of the 2019 French Open, Barty raced through the opening set in 24 minutes and led 2-1 in the second before Muchova requested an off-court medical timeout on Rod Laver Arena.

It was a turning point, Muchova returning reinvigorated as the unheralded Czech reached her maiden major semi-final in remarkable fashion, with the 24-year-old revealing during her on-court interview, "I was a bit lost [gestures at head] on the court and my head was spinning so I took a break. It helped me.

"It was more they just checked my pressure because I was a bit lost. I was spinning. So they cooled me down a bit with ice and it helped me."

Asked about Muchova's actions, Barty told reporters: "It's within the rules. She's within her rights to take that time. If she wasn't within the rules, the physios and the doctors would have said so. That's the laws of our game, is that we have those medical timeouts for cases that are needed. Obviously she needed that today. Completely within the rules for her to take that.

"From my point of view, I've played a lot of matches where there have been medical timeouts. I've taken medical timeouts myself before, so that shouldn't be a massive turning point in the match. I was disappointed that I let that become a turning point. I'm experienced enough now to be able to deal with that. It's a disappointment today without a doubt. But we learn and we move on."

Barty added: "I would have liked to have just been a little bit sharper the next game. Started well with the first point, just made a couple loose errors in that game. I think for the rest of the set, that was the story, it was just over and over-made. Probably pressed a little bit trying to be overly aggressive.

"Had some break points, I think it was that three-all, that was probably a bit of a critical game in the momentum there for the second set. Just disappointed with the fact that I wasn't able to bring the match back on my terms after she took that break."

"I didn't hear what she said when she called for the trainer," Barty continued. "That's not my decision. When you call for the trainer, you obviously tell the umpire what the reason is. And then the doctor and physios come out and assess it. That's within the rules. For me, that's not really my decision and not my concern what she took the medical for.

"Obviously there are rules when we go off the court for whatever areas you're getting treated because that's quite normal. But, yeah, that's not really my decision to make on whether or what her medical condition was or what the timeout was for."

Brady, who tallied 31 unforced errors in the final two sets having only managed six in the first, said: "It's heartbreaking, of course. But will it deter me, will it ruin the fact we've had a really successful start to our season? Absolutely not.

"The sun will come up tomorrow. We go about our work again. You're either winning or you're learning. I think today is a massive learning curve for me, for Tyz [coach Craig Tyzzer], my team as well. We take the positives out of it, without doubt and don't let this particular match, this particular hour of tennis deter us from what we're trying to do."

Australian Open fans are set to return to Melbourne Park from Thursday after the Victorian government confirmed the lifting of restrictions following a five-day lockdown amid the coronavirus pandemic.

While the number of supporters set to attend remains unknown, fans will be back in their seats for the beginning of the Australian Open semi-finals, with record-chasing Serena Williams set to face three-time grand slam champion Naomi Osaka in Melbourne.

Defending men's champion Novak Djokovic will play the tournament’s surprise package, Russian qualifier Aslan Karatsev - who is the first player to reach a semi-final on their grand slam debut.

Djokovic was on court when the lockdown came into effect last Friday, with the five-day "circuit-breaker" designed to control an outbreak of the UK coronavirus strain.

Part of the third round, the fourth round and quarter-finals of singles action were played behind closed doors after a series of outbreaks in Victoria.

The state has recorded 12 more active cases since the lockdown was implemented but, with none discovered in the past 24 hours, Victorian premier Daniel Andrews announced restrictions will be eased.

"I'm very, very pleased to announce that the restrictions will come off, almost all of them, at midnight tonight," Andrews told reporters on Wednesday.

"From 11:59pm [Wednesday local time], the restrictions will be dropped [but] masks will be required indoors and outdoors when you can't socially distance."

The stage-four restrictions meant residents could not leave their homes for any other reason than work, shopping for groceries, exercise or the giving or receiving of medial care.

This year's delayed Australian Open has had crowds capped at 30,000 per day with original COVID-19 restrictions, but new limits are yet to be determined for the rest of the tournament.

"There will be meetings this afternoon [to determine] what is a safe number," Andrews said.

"They already were reduced, they may have to be reduced further, but that matter will be resolved in the next few hours."

Liverpool took charge of their Champions League last-16 tie with RB Leipzig as they claimed a 2-0 win in the first leg in Budapest.

Julian Nagelsmann's side, who pipped Manchester United to a place in the knockouts, looked far from comfortable in the unfamiliar surroundings of the Puskas Arena, where Tuesday's game was held to due to coronavirus travel restrictions.

Mohamed Salah's 24th goal of the season put Liverpool ahead after a mistake by Kevin Kampl, and Sadio Mane doubled the advantage when Nordi Mukiele gifted him an opportunity.

The Reds are now unbeaten in six away games against Bundesliga opposition stretching back to 2002, and Jurgen Klopp's men will be firm favourites to progress to the quarter-finals.

Liverpool nearly fell behind after just five minutes, Dani Olmo's diving header hitting the inside of the post from Angelino's cross.

The away side looked the most threatening as they began to take control, and Peter Gulacsi was alert to block a Salah effort from close range before Roberto Firmino fired a shot into the side-netting.

Mane then headed over from six yards from a Firmino cross, and the Senegalese thought he had set up his strike partner to nod in the opener after errors from Dayot Upamecano, but the ball had gone out of play.

Christopher Nkunku had barely been involved in the first half but he could have given Leipzig the lead early in the second, Alisson saving well after the striker ran onto Olmo's throughball.

It was Salah who broke the deadlock 53 minutes in, drilling past Gulacsi after a dreadful backpass from Kampl, and it soon got worse for Leipzig.

Mukiele made a complete mess of a simple clearance forward by Curtis Jones, and Mane had time to stride into the box and slot home.

Angelino had a chance to pull a goal back but sliced his attempt badly, summing up a poor game for last season's semi-finalists.

What does it mean? Fragile Liverpool give season huge boost

Injuries and recent form - they had won three of their previous 12 games in all competitions - will have had Liverpool fans feeling a little anxious before meeting the side second in the Bundesliga.

However, a display of supreme authority, helped by an erratic approach from Leipzig, put Klopp's men in total charge of this tie and could well have provided a timely boost in confidence.

Leipzig will hope for better in the second leg, but their previous visit to England ended in a 5-0 defeat to Manchester United.

Salah at menacing best

Salah should perhaps have scored sooner but he made no mistake with his clearest chance of the game.

He spent the rest of the game harassing a deeply unsettled Leipzig defence in a hugely impressive, committed performance.

Nagelsmann's men in a muddle

Leipzig were on a six-game unbeaten run at home in this competition and it was unfortunate for them that this game had to be relocated to a neutral venue.

Still, that does not explain the horribly haphazard nature of their performance. Two defensive errors led directly to the goals, Mukiele could have been sent off before his mistake, while Bayern Munich-bound Upamecano misplaced 20 passes from centre-back.

What's next?

With the return leg not until March 10, Liverpool's more pressing concern is a derby with Everton on Saturday. Leipzig head to Hertha Berlin in the Bundesliga a day later.

Joao Felix is back in contention for Atletico Madrid after being sidelined with coronavirus, Diego Simeone has confirmed.

It was confirmed Portugal international Joao Felix tested positive for the virus on February 3, forcing him to miss two games for LaLiga's leaders.

The first was a 2-2 draw at home to Celta Vigo, who netted a late equaliser, before Atleti beat Granada 2-1 in Andalusia on Saturday to stay five points clear at the summit with two games in hand on second-placed Real Madrid.

Moussa Dembele, Thomas Lemar and Hector Herrera were all confirmed as having the virus in the five days after Joao Felix's results were returned, but the situation has had minimal impact on the team's on-field performances.

Up next is a trip to Levante on Wednesday, before hosting Paco Lopez's men at the weekend, and that is followed by the first leg of their Champions League last-16 tie with Chelsea.

Simeone is unsure if Joao Felix will feature on Wednesday but was glad to have him back.

"He has not had many symptoms that left him unable to train at home, so he was working with the coaches since the fourth day [of his absence]," Simeone told reporters.

"He is eager and enthusiastic, he is healthy. It's great to be able to count on him tomorrow, but we will decide tomorrow what to do with him."

Attention soon turned to Atletico's other key attacker this term, Luis Suarez, who has recently been the subject of reports claiming the Uruguayan has a clause in his contract that would allow him to leave on a free transfer at the end of the season.

Simeone seemed unimpressed he was even asked the question.

"Normally I don't talk about personal contracts," Simeone said.

"I talk about how to attack, how to play, but I don't interfere in personal matters."

Ben Simmons believes his potential is "scary" after scoring a career-high 42 points against the Utah Jazz.

Playing at center in the absence of Joel Embiid for the Philadelphia 76ers, Simmons converted 15 of his 26 field goals, adding 12 assists and nine rebounds in a fantastic performance.

Utah still won the game 134-123 to make it 19 wins from 20.

Despite playing in a third straight loss, Simmons believes the record night shows he has made huge strides over recent weeks.

"I feel like I'm figuring it out," Simmons said after the game.

"Obviously, my scoring has been a lot higher the past five, six games.

"As long as I can keep doing that and stay locked in and keep working on my mental [game], I think it's scary.

"You have got to keep your foot down. Keep pushing forward offensively with me. Stay dominant - I know what I'm capable of.

"It felt good that I was able to dominate offensively. Defensively I did okay, not great. Offensively, I definitely had to pick up the slack especially if Joel is out. So yes [it was probably my most aggressive game].

"I loved when I saw Rudy [Gobert] was guarding me. I love being able to go at somebody like that. I felt like it was a little bit disrespectful to put him on me, but it is what it is.

"Honestly, I've just been working on my mentality and mental [game] a lot these past few weeks.

"It's not easy to do that. Your mindset will change the way you play or certain things in the game that come natural for certain people. It is all mental.

"People don't realise your mentality is a huge part of the game. For me I continue to work on that. I'm just trying to get better and progress my game and get to that next level.

"But we wanted to get this win bad. We didn't get it, so we've got to move on."

Getting Simmons matched up with Gobert was exactly what coach Doc Rivers had in mind, while he also praised Tobias Harris for a 36-point display.

Rivers said: "I didn't know we were going to get the 42 points out of him! But he did everything - he guarded, did a good job. Played with pace.

"We anticipated once Joel scratched that the lineup that we put on the floor, we were trying to create a lineup where Gobert would guard Ben and that happened.

"The key for us was getting stops and getting it to Ben and getting up the floor. We just felt like there was no way anybody was going to stay with Ben, especially a center.

"Tobias [Harris] was phenomenal as well. Look at those two guys, man!

"Harris has to be straight line, aggressive and powerful. When he plays like that, he's hard to deal with. He played a very decisive game and had very few indecisive plays.

"He is really keeping the game simple, playing with great force, scoring from the three[-point line], off the dribble and the post. He's doing exactly what we believe he can do.

"[Embiid] was just a late scratch. They came to me and told me his back is still stiff. So I don't think this is a long term issue or anything like that. It's just a game missed."

The Sixers are still top of the Eastern Conference at 18-10 and host the Houston Rockets next on Wednesday.

Jordan Clarkson scored 40 points off the bench for the impressive Jazz, who lead the Western Conference with an NBA-best record of 23-5.