MELBOURNE: Eight-time champion Novak Djokovic was made to sweat at the Australian Open on Wednesday as Serena Williams made serene progress in her bid for a record-equaling 24th Grand Slam title.

Women鈥檚 favorite Naomi Osaka also charged through but fellow major winners Stan Wawrinka, Bianca Andreescu and Petra Kvitova were all second-round casualties.

Among the late matches, Aussie crowd-pleaser Nick Kyrgios served underarm, smashed a racquet and rowed with the chair umpire before coming from behind to beat France鈥檚 Ugo Humbert in five gripping sets.

Earlier, Djokovic was given a stern examination by American Frances Tiafoe and dropped his first set of the tournament before recovering to win 6-3, 6-7 (3/7), 7-6 (7/2), 6-3.

鈥淚 was fortunate to get through the third set today, it was anybody鈥檚 game,鈥� said the defending champion, after his win in hot conditions in Rod Laver Arena.

The top seed looked in control after taking the first set, but lightning-quick Tiafoe, who reached the quarter-finals two years ago, refused to go away.

The American bounced back to take a close second set but imploded as tensions rose in the fourth, receiving a code violation for an audible obscenity as Djokovic took charge.

The Serb is targeting a record-extending ninth title and his 18th Grand Slam trophy overall as he snaps at the heels of Rafael Nadal and Roger Federer, who top the all-time list with 20 each.

Djokovic avoided the fate of 2014 winner Wawrinka, who blew three match points in the fifth-set tiebreaker of his four-hour epic with Marton Fucsovics, who won 7-5, 6-1, 4-6, 2-6, 7-6 (11/9).

鈥淚 hesitated a little bit when I had the match point and I lost it,鈥� said the 35-year-old Swiss, a three-time Grand Slam winner. Osaka, whose three Grand Slam titles include the 2019 Australian crown, had no such trouble in her evening match against France鈥檚 Caroline Garcia 鈥� despite fearing defeat after a bad dream.

鈥淟ast night I had a dream that I lost this match, and I really didn鈥檛 feel good about it,鈥� she said after the 6-2, 6-3 win.

Second seed Simona Halep survived a scare when she reeled off five third-set games in a row to avoid defeat by Australia鈥檚 Ajla Tomljanovic.

鈥淚 fought till the end. I never gave up during the match, and that鈥檚 why maybe I could win in the end,鈥� said the two-time Grand Slam winner.

Williams, 39, continued her quest to equal Margaret Court鈥檚 all-time mark of 24 Grand Slams with a 6-3, 6-0 romp past 99th-ranked Serbian Nina Stojanovic.

Williams hit 27 winners in her 101st Australian Open match while again sporting her unique, one-legged catsuit inspired by track legend Florence 鈥淔lo-Jo鈥� Griffith Joyner.

鈥淚鈥檓 here to have fun and it鈥檚 great to be playing in front of a crowd,鈥� said Williams.

With Australia virtually virus-free, the tournament is welcoming the biggest Grand Slam crowds since the pandemic, although attendances are well down on previous years.

A socially distanced John Cain Arena was rocking for the Kyrgios match, where the unseeded home favorite denied Humbert what seemed like a certain win to set up a clash with US Open champion Dominic Thiem.

鈥淗onestly, I don鈥檛 know how I did that,鈥� said Kyrgios after the unlikely 5-7, 6-4, 3-6, 7-6 (7/2), 6-4 victory.

鈥淚 don鈥檛 even know what to say, I鈥檓 lost for words. That is one of the craziest matches I鈥檝e ever played.鈥�

German sixth seed Alexander Zverev went through in less compelling fashion, grinding past America鈥檚 Maxime Cressy 7-5, 6-4, 6-3.

Williams鈥� elder sister Venus, 40, was among the casualties on day three when she painfully rolled her ankle in the first set against Sara Errani before hobbling through a 6-1, 6-0 defeat.

And Andreescu, the 2019 US Open champion who missed the entire 2020 season with a knee injury, saw her comeback come to an abrupt end 6-3, 6-2 against Taiwan鈥檚 Hsieh Su-wei.

Elsewhere Kvitova, the former Wimbledon champion and Melbourne runner-up in 2019, committed 44 unforced errors in her 6-4, 1-6, 6-1 defeat to Romania鈥檚 Sorana Cirstea.

However Thiem, runner-up to Djokovic last year, was all smiles as he beat Germany鈥檚 Dominik Koepfer 6-4, 6-0, 6-2.

Eighth seed Diego Schwartzmann of Argentina beat France鈥檚 Alexandre Muller 6-2, 6-0, 6-3, while Canada鈥檚 Milos Raonic won 6-7 (1/7), 6-1, 6-1, 6-4 against another Frenchman, Corentin Moutet.