Andy Roddick reached the fourth round of the Sony Ericsson Open in Key Biscayne, Florida, on Sunday after overcoming two set points in the tiebreaker to beat Dmitry Tursunov of Russia 7-6 (9), 6-2.

Andy Roddick stretches to return to Dmitry Tursunov of Russia in the third round at the Sony Ericsson Open in Key Biscayne, Florida, on Sunday. Roddick won 7-6 (9), 6-2. [Shanghai Daily]

The fifth-seeded Roddick erased one set point with an ace and the second when Tursunov netted a forehand. He won the final three points in a grueling 75-minute first set. Roddick finished with 11 aces and faced only one break point.

Roddick, who improved his record this year to 25-4 and leads the ATP Tour in victories, lost his temper early in the set when mist fell and umpire Cedric Mourier declined to stop play. After losing his serve, Roddick slammed down his racket, picked it up and threw it again.

"I basically was wondering how many more times we were going to play on a slippery court," Roddick said. "He said, 'Well, no one has fallen yet.' I said, 'Well, if that's a barometer, then we have a problem.' So I feel like my argument was just, but the way I went about it probably wasn't the best."

Roddick missed many chances in the first set to make his match shorter. With the No. 25-seeded Tursunov serving at 5-all, Roddick failed to convert five break-point chances and finally sailed a forehand long to lose the 22-point game. He also was unable to convert his first three set points in the tiebreaker.

Roddick said gusty wind and high humidity made conditions difficult, so he was content to keep the ball in play and wear Tursunov down with a series of long rallies.

Second-seeded Roger Federer beat Nicolas Kiefer for the 11th consecutive time, 6-4, 6-1. Roddick's next opponent will be No. 9 Gael Monfils, who rallied from two service breaks down in the final set to beat Marat Safin 5-7, 7-5, 7-6 (3).

Top-ranked Serena Williams made the round of 16 by beating Peng Shuai 7-5, 6-2. No. 5-seeded Venus Williams defeated Anna-Lena Groenefeld 7-5, 6-3. Serena will face another Chinese player next - Wimbledon semifinalist Zheng Jie.

No. 7-seeded Ana Ivanovic, the defending Roland Garros champion, lost to No. 25 Agnes Szavay 6-4, 4-6, 6-1. No. 2 Dinara Safina was beaten by unseeded Samantha Stosur 6-1, 6-4. Vera Zvonareva went out to China's Li Na 4-6, 6-3, 2-6.

(Agencies via Shanghai Daily March 31, 2009)