Maria Sharapova expects Sloane Stephens to be a grand slam rival for many years to come.

Defending champion Sharapova reached the quarter-finals at the French Open this evening with a 6-4 6-3 victory over Stephens, who battled extremely hard.

In the last eight Sharapova will play old foe Jelena Jankovic, whose resurgence continued with a 6-0 6-2 victory over America's Jamie Hampton.

Twenty-year-old American Stephens is at the forefront of the next generation in women's tennis and proved she can handle the big stage by beating Serena Williams in the last eight at the Australian Open in January.

"It was just refreshing to just get back on the court and just compete and have fun and enjoy myself" - Sloane Stephens

Stephens won only three games when she met Sharapova in Rome last month, and the Russian said: "This is a different stage and I'm sure she was geared up.

"Especially when you lose a couple of weeks ago, you want a bit of revenge. I'm sure she had that type of feeling going into that match-up today.

"I think she has a tremendous amount of potential. It's also a bit of a different generation. She's 20, that's the new 17.

"There are some players which you play against and you're not quite sure if they will be able to develop something to a different level.

"But I think there's a lot of room for a few things to improve, and I think she will.

"This is a really important time in her career. If she's in the right hands at the right time, I'm sure she's going to have a great career."

Stephens had struggled since Australia while she also earned unwanted headlines for an interview where she criticised Williams.

Stephens was happy with her run in Paris, saying: "It was just refreshing to just get back on the court and just compete and have fun and enjoy myself.

"It's obviously been a stressful couple of months, so just to get out and not have to worry about anything and just play, it was fine."

Sharapova and Jankovic were both at Nick Bolletieri's academy and played their first tour-level match nine years ago. The Russian has come out on top in seven of their eight matches, including earlier this year in Miami.

Four American women reached the last 16, the best showing at a grand slam since the US Open in 2004, but only Serena Williams is left after Bethanie Mattek-Sands joined Stephens and Hampton in exiting the tournament.

It has been a great week for Mattek-Sands, who beat former French Open champion Li Na in round two and was making her first appearance in the last 16 at Roland Garros.

She led 4-1 against 12th seed Maria Kirilenko but the Russian fought back to win 7-5 6-4 and now plays third seed Victoria Azarenka.

Mattek-Sands called for the doctor leading 5-4 in the opening set, while Kirilenko also took a medical time-out for treatment to her right shoulder in the second set but came through.

Kirilenko questioned her opponent's time-out, saying: "I was a little bit surprised. I was thinking she was kind of joking with me, so it was a little bit not maybe nice from her. Maybe she really had some problems. I don't know."

Mattek Sands explained: "It's that time of the month. I just needed a pill. The doctor gave me what he had and it helped."

Azarenka looked in fine form today, beating former champion Francesca Schiavone 6-3 6-0.

The third seed has never previously been beyond the quarter-finals at Roland Garros but she is encouraged by the progress she has made on clay.

Azarenka said: "I think I'm learning more now and I'm adjusting much better.

"There's no doubt it's been always the most challenging (surface) for me, but I feel like I'm finally understanding what I need to do to improve.

"I feel it's a process, but I'm on the right way. That's the most important for me, to it take step by step. I hope I'm playing better than before, because otherwise that would be a step back.

"But I'm happy with the way my progress is going, and we'll see what happens next."