The Russian mounted a comeback after losing the first eight games and served for the second set, but she played a poor game and Errani reeled off four games in a row.

The 25-year-old has had a superb season, winning three titles, all on clay, as well as making the last eight at the Australian Open, and in the quarter-finals here she will play 10th seed Angelique Kerber.

The German's rise has been one of the stories of the past year. She was ranked outside the top 70 when she lost to Laura Robson in the opening round at Wimbledon last summer and by August had dropped out of the top 100.

But she went all the way to the semi-finals at the US Open later the same month and has not looked back.

She has already won a title in Paris this season and another in Copenhagen, and today she was too good for 21-year-old Croatian Petra Martic, coming through 6-3 7-5 on Court Suzanne Lenglen.

The weather at Roland Garros today was cold and windy, a far cry from the hot and fast conditions of the first week, which certainly did not help Kuznetsova.

The Russian has had a poor season, and she said: "The first set was just horrible. Today the weather was so bad. I felt cold during the whole match. For me to move was really complicated. I could not make my feet work.

"Then in the second set I started to play better, hitting the right shots at the right time. But at 5-3 I just didn't do the right thing. Maybe I rushed too much.

"It's the best I've seen Sara play. Her game is very good on clay. I'm far away from my best form yet."

Kerber, 23, turned professional at the age of 15 and has taken her time to make the breakthrough, but she always believed she had the ability.

The German said: "I'm not surprised because I know that I can play good. I showed years ago that I could play good matches against top players, but I never won those matches. That's changed. Now I play good, and also I can win."