Serena Williams has been knocked out of the Australian Open in dramatic fashion, falling in a three-set thriller to 27th seed Qiang Wang.

The Chinese underdog stunned Williams in a 6-4 6-7 7-5 victory – a result that is even more remarkable when you consider the American demolished the same opponent 6-1 6-0 at last year's US Open.

Channel 9 presenter Rebecca Maddern called Williams' defeat "undoubtedly the biggest upset of the tournament so far".

Wang remained cool and composed throughout the match as she completed the biggest win of her career.

Advertisement

"I think my team always thought I could do it," she said in her on-court interview.

"After last time, I did really hard work on court and off the court. It's really good work. I believed I could do it."

The eighth seeded Williams lost the first set to Wang and went down a break in the second as she faced a 3-5 deficit, just one game away from exiting the tournament.

In commentary for Channel 9, former Australian player Jelena Dokic said: "This is unbelievable. I think everyone is in shock at what is happening here."

But Williams won an incredible rally to break back and get things back on serve at 4-5, before the set went to 6-6, forcing a tiebreak.

The American, who won the ASB Classic earlier this year, then put the squeeze on Wang, pushing her around the court and out-lasting the Chinese player in gruelling rallies as she claimed the breaker 7-2 to send the match to a deciding third set.

Neither player could pull away and the final set edged to 3-3 as the tension rose inside Rod Laver Arena.

But serving at 5-6, Williams stumbled and gave Wang two match points. She saved the first then forced the game to deuce when Wang clunked a simple groundstroke into the net.

Advertisement

Wang wouldn't fall again though, hanging firm and breaking the American to secure a remarkable upset.

'Absolute stitch-up': Barty has a laugh after latest win

Ash Barty is through to the fourth round after defeating Elena Rybakina in straight sets 6-3 6-2.

The Aussie made a rough start to the match, serving first but failing to register a point as Rybakina broke her to love.

Australian Ash Barty during her match against Elena Rybakina of Kazakhstan. Photo / Getty Images
Australian Ash Barty during her match against Elena Rybakina of Kazakhstan. Photo / Getty Images

Barty broke straight back to level things up at 1-1 but the rollercoaster continued when two more breaks made it 2-2, with neither player able to hold serve in the opening four games.

Barty finally became the first woman to win a game on her own racquet when she held for a 3-2 advantage.

After her ugly opening the hometown hero was starting to find her groove and raced to 5-2 before closing out the first set 6-3.

Barty consolidated her early break in the second set, holding serve in what was the longest game of the match to go 2-0 up.

She maintained the rage and charged effortlessly to 5-1 before wrapping up the match in one hour and 18 minutes.

"It's the best I've played this summer so far," Barty said. "It's just nice to get another opportunity to come out and enjoy it."

Barty is a gun all-round athlete, having played professional cricket, and has been seen warming up by kicking a footy before her matches.

Asked if there was someone she enjoys having a kick with the most, Barty threw her strength and conditioning coach Mark Taylor under the bus.

"This is an absolute stitch-up for Tubs right now. My S&C trainer cannot catch a ball to save himself so we just keep drilling him every single day," Barty said.

"It's the highlight of my day, every day.

"Sorry Tubs."

Schwartzman wins, Wozniacki rebounds

Diego Schwartzman beat Dusan Lajovic 6-2 6-3 7-6 to progress to the fourth round.

The 14th seed was in control for the opening two sets before finding the third tough going, but still triumphed 9-7 in a tiebreaker to seal victory.

Caroline Wozniacki, who will retire after the Australian Open, found herself in trouble after dropping the first set 5-7 to Ons Jabeur but squared things up by taking the second 6-3 to take the match to a decider.

Aussies go down

The ageless Lleyton Hewitt was knocked out in the first round as he partnered fellow Aussie Jordan Thompson in doubles.

The pair dropped the first set 6-2 to Koreans Ji Sung Nam and Min-Kyu Song before losing the second 6-3 to bow out in 56 minutes.

It was similarly bad news for another Australian team of Chris Guccione and Matt Reid, who also lost their doubles match in straight sets.

On Margaret Court Arena, Diego Schwartzman grabbed the opening two sets over Dusan Lajovic.

Rafa's brilliant wife sledge

Rafael Nadal melted hearts by kissing a ballgirl on the cheek after the Spaniard blasted a stray forehand into her head during his second-round win last night.

In his post-match interview with former Aussie star Sam Groth, Nadal was told "don't worry about your wife for a second" as the world No. 1 had some fun and cracked the crowd up with a brilliant one-liner.

Rafael Nadal of Spain smiles after his second-round match against Federico Delbonis of Argentina. Photo / Getty Images
Rafael Nadal of Spain smiles after his second-round match against Federico Delbonis of Argentina. Photo / Getty Images

"No no, I'm not worried at all," Nadal said as the cameras panned to his wife, who he married last year, watching on in the stands.

"Probably after 15 years (together) she doesn't care much."