Sharapova in sizzling form

But Sharapova had twice fought back from similar positions in earlier rounds, and she won six of the next seven games to level the match.

Kuznetsova, who is still considering legal action over the accusations she failed a drugs test at an exhibition in December, was finding it impossible to hold serve and by the end of the match had been broken eight times in succession.

Kuznetsova, seeded fifth, handled the heat better than her rival but not her own racket. She was critical of her sloppy play. In addition to the errors, Kuznetsova was successful with just 46 per cent of first serves.

After the first set Kuznetsova said it was "like my body was there, but my mind wasn't there at all".

She added: "I didn't do anything to win this match. I didn't deserve to win because I just didn't fight. In the second and third set, I just went off. I just stopped. It was just, I don't know, ball-boy playing out there."

The final break saw Sharapova win the best point of the match to seal victory, the 17-year-old desperately keeping the ball alive before producing a superb forehand winner to reach only her second Grand Slam semi-final. Asked how much she had left at the finish, Sharapova said it was "just enough to win that match point, that's it".

In contrast, Williams had an easy victory over second seed Amelie Mauresmo.

Williams had won eight of the pair's previous nine meetings, including coming from a set down in the semi-finals of the season-ending tour championships last year. The 2003 Australian Open champion was always in command against the French woman today, breaking serve twice in the first set to take it 6-2.

The second set followed a similar pattern, with Williams breaking twice more before completing a 6-2, 6-2 win with her fifth ace. "I feel great, I played really solid and did not make too many errors," said Williams, who had complained that her serve has been causing her problems throughout the tournament so far.

"I was really focused. I knew I was playing a great player, I had to be really serious."

Mauresmo had her left thigh heavily strapped and admitted it had severely hindered her in the match.

"Tennis is tough enough when you are 100 per cent, when you are 50 per cent it is getting tougher and tougher to win. What can I do?" she said.

"It got worse during the last match, I thought I would recover well with a day of rest but it was not the case. It is frustrating. I thought I could play at maybe 90 per cent today.

"She had nothing to do but put the ball back in. You can't really judge her game today."

Williams didn't win a major title in 2004, losing the Wimbledon final - as the two-time defending champion - to Sharapova.

She later bristled at suggestions that she and sister Venus - the duo have combined for 10 Grand Slam titles - are on the decline and that she needs to win here to prove otherwise.

"I'm tired of not saying anything, but that's not fair," said Williams.

"We've been practicing really hard. We've had some serious injuries. We're not declining. I don't have to win this tournament to prove anything. I know that I'm one of the best players out here."

Venus was knocked out yesterday by home hope Alicia Molik.

The 10th seed is bidding to become the first Australian woman to win the title since Chris O'Neil in 1978. The 23-year-old will meet top seed and world No1 Lindsay Davenport for a place in the semi-finals.

In the remaining quarter-final, Nathalie Dechy of France - through to her first grand slam quarter- final at her 37th attempt and seeded 19th - plays Switzerland's Patty Schynder tomorrow.