Maria Sharapova believes Petra Kvitova is the "one to beat" as she prepares to face the Wimbledon champion in their Australian Open semi-final on Thursday.
Czech Kvitova, 21, beat the 24-year-old Russian 6-3 6-4 in last summer's Wimbledon final.
"I've lost to her the last couple of times - including obviously the big one at Wimbledon where she played really well," said the Russian.
"She's the one to beat right now, she's playing the best tennis of her career.
Sharapova added: "I don't like losing so many times in a row so I'll certainly be going out there and trying to play my best."
Her opponent said: "I have to play my game as always and be aggressive. If I'm focused on every point then it's easy."
The Australian Open women's semi-finals carries extra intrigue this year, with three of the four players in the running to take over the world number one spot from Caroline Wozniacki.
Fouth seed Sharapova, who clinched the title in 2008, must win the title, while number two Kvitova has to match or better the run of Victoria Azarenka, who faces Kim Clijsters in the other semi.
"The girls that are trying to get there haven't been in that position before," said former number one Sharapova, who has dropped one set and lost 21 games in five matches at this year's Australian Open.
"I've been fortunate to have been there."
Meanwhile, third seed Azarenka, 22, said she was wary of Clijsters' experience and Grand Slam record - four career titles, including victory last year in Melbourne.
"Kim is a great champion. She knows how to deal with such a situation and handle big matches," she said.
"But we'll see. I'll just try to stay fresh out there and keep playing my game."
Clijsters, 28, is carrying an ankle injury she suffered in her fourth-round win against Li Na.
The Belgian said she has had little time to concentrate on her opponent during preparations, as she described her recovery programme.
"I lie on the couch, then put on ice for 20 minutes, then take it off for 20 minutes, then put on ice again for 20 minutes and then 20 minutes off. It's leg elevated, lymphatic drainage, all that stuff," said the number 11 seed.
"Instead of really focusing on the match, you're focusing on trying to get the ankle as good as possible."