American Andy Roddick made his way safely into the Australian Open semifinals for the fourth time, leading defending champion Novak Djokovic 6-7(3), 6-4, 6-2, 2-1 when the Serbian retired on a sweltering Tuesday in Melbourne.

The Serbian world number three, who broke through for his first Grand Slam win here last year, won the tie-break of the first set, but looked listless in the remaining match under a scorching sun despite asking for a medical timeout.

The first set saw both players hold solid serve, but Roddick, taking advantage of a sluggish Djokovic, broke his opponent four times in the second and third sets to retain the momentum in his favor.

Earlier, Russian Vera Zvonareva continued to dominate her head-to-head record against Frenchwoman Marion Bartoli with a runaway 6-3, 6-0 win in the women's singles quarterfinals.

"I don't know what happened, I thought Marion was playing really well in the beginning, but I was able to cut down on my unforced errors and keep a good level of play throughout the rest of the match," said Zvonareva, who now advances to her first Grand Slam singles semifinal.

"I was able to play a very, very clean match today. That's what made the difference."

But No.16 seed Bartoli should have pulled off a strong form which lifted her over world number one Jelena Jankovic in the round of 16. In that match, the Frenchwoman hit as nearly twice as many winners against the Serb.

"I think she played just unbelievably well. She barely miss one ball. I was hitting as hard as I could. She was coming back with some better shots," said Bartoli, who led 3-1 in the opening set in the quarterfinal.

"Even when she was scrambling, she was putting the ball just ten centimeters from the baseline. It seems like she's reading my game like in the book. It was just too good."

(Xinhua News Agency January 27, 2009)