MELBOURNE, Australia (AP) Maria Sharapova held her end of the bargain, beating Belinda Bencic 7-5, 7-5 on Sunday to reach the Australian Open quarterfinals and a possible rematch of last year's final with Serena Williams.
The fifth-seeded Sharapova fired 21 aces and hit 58 winners but needed 2 hours, 5 minutes to beat Bencic on her second match point, converting it with a successful challenge after her forehand was initially called long but getting it overturned when the ball tracker showed it hitting the baseline.
Sharapova screamed in delight after the successful challenge, and Bencic stood for a while and had to ask the chair umpire if the match was over.
''This must be the first match I won on a challenge but it felt like a clean ball - I felt like it was on the line, I was really positive about it but I thought worst-case scenario we're back to deuce.''
Six-time champion Williams was playing No. 58-ranked Margarita Gasparyan in the next match on Rod Laver Arena. Unlike Sharapova, who had to play under the roof because play started while it was lightly raining, Williams was playing with the roof open on the main arena at Melbourne Park.
Sharapova, who won the title in 2008 and lost three finals at Melbourne Park, predicted a rematch with Williams in the next round.
''I expect to play her - I look forward to playing the best in the world and that's what she's proven in the last year,'' she said.
The 18-year-old Bencic, playing in the fourth round of a major for only the third time, again found herself on the wrong end of an opponent's aces count. Sharapova had 21, including four on her second serve. Last year, Bencic was on the receiving end of a WTA-record 27 aces from Sabine Lisicki.
Kei Nishikori was the first male player through to the quarterfinals, beating No. 9-seeded Jo-Wilfried Tsonga 6-4, 6-2, 6-4 in front of a partisan crowd filled with flag-waving Japanese fans.
The seventh-seeded Nishikori, the 2014 U.S. Open finalist, also reached the quarterfinals at the Australian Open last year and in 2012.
Nishikori has had trouble with Tsonga's power game in the past, losing most recently to the Frenchman in the quarterfinals of the French Open last year.
But Tsonga lost his serve five times in the match and only managed to break Nishikori once.