Vaidisova floors Mauresmo on home ground

She has flowing blond hair and striking good looks, speaks English with a Floridan accent that belies her eastern European roots and hits the ball with formidable power.

Nicole Vaidisova would also prefer to be acclaimed in her own right rather than as the next Maria Sharapova, an ambition that will have been helped hugely by yesterday's fourth-round matches here at the French Open. Vaidisova, a 17-year-old Czech who is already the world No 16, provided the biggest shock of the tournament so far by knocking out Amélie Mauresmo on the same day that Sharapova was beaten by a fellow Russian, Dinara Safina.

Mauresmo had been trying to convince herself that this would be her year at last, but the world No 1 failed once again on the stage where she yearns to succeed more than any other. The Frenchwoman finally broke her Grand Slam duck this year by winning the Australian Open (where she conceded only two games to Vaidisova in the fourth round) but the old frailties reappeared here.

Vaidisova, who won 6-7, 6-1, 6-2, is an attacking baseliner with a sweet forehand, penetrating serve and powerful physique who has been at Nick Bollettieri's academy in Florida since she was 11. She has already won six senior tournaments.

Mauresmo won the first set tie-break, having failed to serve out at 5-4, but Vaidisova raced into a 5-0 lead in the second set, which she won with an ace, and took the first four games of the decider. Mauresmo briefly fought back, but Vaidisova held her nerve.

"I'm just very excited," the Czech said. "This is the first time I've got to the quarter-finals of a Grand Slam tournament, the first time I've beaten Amélie and the first time I've beaten a world No 1."

Mauresmo said: "I didn't feel I was getting nervous, especially looking at the way I played in that first set, but my shots weren't powerful or long enough. I played with less intensity and wasn't dictating the points."

Sharapova, who has been out for two months with an ankle injury, lost 7-5, 2-6, 7-5. Two points from victory when serving at 5-2 in the third set, she suddenly appeared to lose all confidence and won only three of the last 21 points. The final exchange was typical as Sharapova played a tentative volley before Safina thumped a backhand cross-court winner.

Although Sharapova said she hoped to compete next week at Edgbaston, which is where she normally plays in the build-up to Wimbledon, she added: "I'll have to discuss it with my team."

Safina, 20, has been in the world's top 100 for four years but it was only last winter that she broke into the top 20. Steady improvement culminated in the best week of her career last month in Rome, where she lost to Martina Hingis in the final.

Her stock has risen as that of her brother has fallen. Marat sent a text message ("great fight, good comeback") after her victory and Safina said she was enjoying being the most successful member of the family: "I used to be just my brother's little sister, so I want this to continue."

Sharapova's successor as Wimbledon champion, Venus Williams, played some fine attacking tennis in beating Patty Schnyder 4-6, 6-3, 6-2. Justine Henin-Hardenne, the defending champion here, dropped just five games in beating the 2004 winner, Anastasia Myskina.

Roger Federer and David Nalbandian, the men's No 1 and 3 seeds, moved into the quarter-finals with straight-sets wins over Tomas Berdych and Martin Vassallo Arguello respectively, which were in strict contrast to the troubles experienced by Rafael Nadal, the No 2 seed, in disposing of Paul-Henri Mathieu over four sets on Saturday.

Gaël Monfils, Andy Murray's conqueror, won his third five-set match in succession to beat James Blake, the No 8 seed, who was unhappy with some shouts from the crowd during play. However, it did not stop Blake enlisting the support of one spectator, who came on to the court to back the American's assertion that the umpire was examining the wrong ball mark during a dispute over a line call.