French Open: Sunday 25 May to Sunday 8 June
Coverage: BBC TV, BBCi, Radio 5 Live and the BBC Sport website.
Safina has been one of the form players on clay this year
Dinara Safina proved her title credentials with a 6-7 (6-8) 7-6 (7-5) 6-2 win over top seed Maria Sharapova in the fourth round of the French Open.
Sharapova had struggled for form in her opening three matches and many tipped her fellow Russian to cause an upset.
And after letting two set points slip by in the opener, Safina saved a match point in the second set before taking control of a tense decider.
She will play compatriot Elena Dementieva in the quarter-finals.
"After my title this season in Berlin, this was one of my best matches and one of my best comebacks," said Safina.
"I knew I could beat her but I put too much pressure on myself and was way too passive. I was too dependent on her and I was 2-5 down in the second set and facing a match point.
"But I hit a winner on her match point and it changed things. Before I was just running and playing the ball back. But I had to focus on myself and not wait for her mistakes and let her dictate.
She's had great success on clay and is a really tough opponent on this surface
"Maybe she went a little down but I went for it and for my shots."
Safina fought back from 5-1 down in the final set to beat Sharapova at Roland Garros two years ago, but had not really built on that result until Berlin last month when she beat Justine Henin and Serena Williams in consecutive matches.
Sharapova, in contrast, came into the tournament as the new world number one but has never enjoyed clay and struggled desperately on serve in her early matches last week.
In a tight first set Safina looked to have the edge but when Sharapova roared back from 6-4 down to take the tie-break, it seemed her champion's mentality would prove the difference.
Safina broke at the start of the second before the rain came, but on the resumption Sharapova stepped up another gear.
She swept through five straight games and got to match point on serve at 5-3, only to see Safina cling on with a blistering backhand.
That was to prove the turning point as the 13th seed forced another tie-break in which she recovered from 5-2 down to level.
The momentum was with her in the decider and she did not waste it, breaking a tiring Sharapova in game six and clinching victory two games later on her second match point.
"I had many opportunities but I guess it was a combination of not taking those chances and being a little unlucky at times," said Sharapova.
"Physically you have to stick with her. She's had great success on clay and is a really tough opponent on this surface.
"It went in the wrong direction really fast. It was just one of those days."
But Sharapova believes she is close to modifying her game to the Roland Garros clay-courts.
"It's a thin line between winning and losing. This stuff isn't easy but I want to do everything perfectly."
Seventh seed Dementieva moved into the last eight for only the second time with a 6-4 1-6 6-2 victory over another Russian, Vera Zvonarena.
Dementieva, the 2004 runner-up, held her nerve the better in an error-strewn match, her famously shaky serve just about holding up.
"I feel like I've done some work, and it's really improved a little bit," she said.
"It's not perfect yet, but I feel more comfortable. It doesn't make me bad or down when I'm serving now."
Zvonareva made a total of 41 unforced errors, repeatedly smacking her racquet into the ground in frustration as the final set slipped away.
Dementieva sealed victory in one hour 48 minutes, gaining revenge for a defeat by Zvonareva earlier in the year.
"What I think that really helped me was the match we played in Charleston in the semi-finals," said Dementieva.
"I think it was a tough match but I learned my lesson.
"Today on the court when I lost the second set I was trying to stay more positive, more aggressive with her, because I know she's a great clay-court player."
Two other fourth-round matches will resume on Tuesday.
Svetlana Kuznetsova leads Victoria Azarenka 6-2 2-2, while Kaia Kanepiof Estonia and Czech Petra Kvitova and are level at 6-3 3-6.