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."

Naomi Osaka said she was "really nervous" before facing Anastasia Pavlyuchenkova but showed no signs of that as she breezed into the second round of the Australian Open.

Osaka looked dominant on day one of the first grand slam of the year as she welcomed being able to play in front of a crowd at Melbourne Park, taking only 68 minutes to wrap up a 6-1 6-2 victory.

The US Open champion has beaten Pavlyuchenkova three times in a row after losing when they first met in 2017 but was wary of facing the Russian on Rod Laver Arena.

Third seed Osaka said: "I was really nervous coming into this match. I know that I've played her before, and it was really tough. I just wanted to play well.

"The most recent memory I have of playing her was in the Osaka final [that Osaka won 6-2 6-3 in 2019], so it's always really hard to play someone that good in the first round.

"For me, I feel like it might have also helped in a way because I calmed my nerves because I felt like I couldn't afford to be that nervous. But, yeah, it was a tough match."

Serena Williams and Simona Halep stormed into round two, but the 2016 champion Angelique Kerber crashed out with a 6-0 6-4 defeat to world number 63 Bernarda Pera.

Alison Riske and Wang Qiang were the only other seeds to fall, losing to teenager Anastasia Potapova and qualifier Sara Errani respectively, while Bianca Andreescu made a winning comeback.

Williams sisters among major winners to make serene progress

Serena Williams did not look at all troubled by a shoulder problem as she started her latest quest to win a record-equalling 24th major singles title with a 6-1 6-1 demolition of Laura Siegemund.

Her older sister, Venus, also advanced in straight sets, beating Kirsten Flipkens 7-5 6-2.

Iga Swiatek, the French Open champion, was too good for Arantxa Rus, winning 6-1 6-3, and Petra Kvitova got past Greet Minnen 6-3 6-4.

Kerber will not be claiming a fourth major crown this month after falling to Croatia-born American Pera.

Halep planning to oust another Australian

Two-time major winner Halep was a cut above Lizette Cabrera, winning 6-2 6-1 in 59 minutes, and is looking forward to facing another Australia in the second round in the form of Ajla Tomljanovic. 

"I like to be here, so I like to play Australians," Halep quipped.

"I feel good. My body is fit. It's always difficult to play a big hitter. So, I have to be strong on my legs, focus on myself and give my best.

"I expected a tough match because I played against her before and I know how it's gonna be. She's a good opponent, a good player, and I will focus just on myself like I do every time, but I'm ready for a good battle."

Andreescu back in business

Andreescu put her injury woes behind her, battling past Mihaela Buzarnescu 6-2 4-6 6-3 in her first match for 15 months.

The Canadian had not played in a grand slam since winning the US Open in 2019 but was back in business on John Cain Arena.

Eighth seed Andreescu said: "After the match, I sat down with my team a little bit, and I'm like, 'Oh, guys, here we go again, those three-setters' and they just started laughing because they obviously knew what they were getting themselves into.

"But those matches are super good for me in my opinion because it really shows that I can scramble when I really need to, or if there's some pressure I can dig my way through it somehow. When my back is against the wall, not only today, but I've noticed throughout my last couple tournaments in 2019, I've been able to pull through with those."

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 and Simona Halep started the season with straight-sets victories in Melbourne a week before the Australian Open gets under way.

Williams and Halep played in an exhibition event with a crowd of 4,000 watching on in Adelaide last Friday and they were back in competitive action three days later.

Legendary American Williams beat Daria Gavrilova 6-1 6-4 to move into the third round of the Yarra Valley Classic.

The fifth seed struck 27 winners to 15 unforced errors on Margaret Court Arena as she set up a meeting with Tsvetana Pironkova, who ousted Donna Vekic 1-6 6-4 6-2.

Williams said: "It was a good match for me. It wasn't easy at all. It was lots of rallies and lots of movement, and she's from here, so she obviously always plays hard. So it was really good and it felt good to clinch that in the end."

Third seed Karolina Pliskova, Petra Martic, Danielle Collins and Marketa Vondrousova also advanced to the last 16 on Monday.

Elsewhere, top seed Halep is through to the third round of the Gippsland Trophy following a 6-4 6-4 win over Anastasia Potapova.

Halep hit 23 winners and broke twice in each set in what was her first official match since October.

Elina Svitolina, the third seed, beat Andrea Petkovic 6-1 6-4, while Coco Gauff, Ekaterina Alexandrova and Jelena Ostapenko were among the other winners seven days prior to the start of the first grand slam of 2021.