Melbourne, Jan 18 (AFP) Five-time Grand Slam winner Maria Sharapova upset defending champion Caroline Wozniacki to reach the Australian Open fourth round Friday after an epic three-set match.

The Russian, who is seeded 30 at Melbourne Park, bundled Denmark's world number three out of the tournament 6-4, 4-6, 6-3 to claim her biggest scalp since returning from a drugs ban in 2017.

Sharapova's win sets up a last 16 clash with in-form Australian hope Ash Barty for the 31-year-old, who won the tile at Melbourne Park in 2008 and has reached the final a further three times.

"I knew I was going to get a really tough match as she's the defending champion of this event and it's no secret she loves this arena," she said after shocking Wozniacki.

"I haven't played many matches in the last year, especially against top players and these are the ones I train for, so it's really rewarding to win."

There were dramatic momentum shifts in the battle between the two former world number ones, but the decisive period came when Sharapova stormed back from 4-1 down to go on a five-game winning streak and take the first set.

After Wozniacki came back she then broke the Dane late in the third set, screaming "come on" after gaining the advantage.

Sharapova won her last Grand Slam at Roland Garros in 2014 and has struggled to rejoin the game's elite since completing a 15-month ban for failing a drugs test. (AFP) APA

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