WIMBLEDON, England - Roger Federer won his 50th straight match on grass, needing only 11 minutes Thursday to complete his 6-2, 7-5, 6-1 victory over 18-year-old Juan Martin del Potro of Argentina to reach the third round at Wimbledon.

The four-time defending champion, who will next face Marat Safin, had led 2-0 in the third set before rain halted play Wednesday. When they resumed, the top-ranked Swiss finished off del Potro, winning three straight games before Del Potro held serve in the sixth game.

"It was done quickly like I was hoping, but I was ready to go five sets in case," said Federer, who broke the Argentine five times and saved the only break point he faced.

No. 2 Rafael Nadal also won, beating Werner Eschauer of Austria 6-2, 6-4, 6-1, and advanced to the third round along with No. 4 Novak Djokovic, No. 6 Nikolay Davydenko and No. 9 James Blake. Four-time semifinalist Tim Heman lost, however.

On the women's side, Maria Sharapova, Venus Williams and Amelie Mauresmo advanced.

The No. 1-seeded Federer, trying to become only the second man in the Open era to win five straight titles at the All England Club, finished with 33 winners and made only 23 errors - one less than Del Potro.

"Fifty is a great number to achieve," said Federer, who is trying to match Bjorn Borg's streak of Wimbledon titles. "I'm delighted about that but I haven't won the tournament.

Two-time Grand Slam champion Safin beat Aisam-Ul-Haq Qureshi of Pakistan 6-4, 6-2, 7-6 (4) to advance.

"He's always a player who can upset anybody on any day. I hope he's not going to have one of those crazy good days against me," said Federer, who edged Safin 6-4 in the third set at last year's grass-court warmup at Halle, Germany. "I feel like I will have to step it up if I want to beat him."

Federer said skipping this year's Halle tournament has not hurt his play, but he did admit to feeling slightly under the weather.

"I have a bit of throat thing going on, but not much," Federer said.

Williams, wearing white spandex shorts instead of a usual skirt or dress, beat Hana Sromova of the Czech Republic 6-2, 6-2 to reach the third round in the women's draw.

"I really haven't played in shorts before, but my skirt was so big," the three-time Wimbledon champion said. "I think they just made it too big."

Williams, who struggled in the first round Tuesday but eventually beat Russian teen Alla Kudryavtseva in three sets, dominated Sromova with her first serves, winning 100 percent of those points in the first set.

"I think my serve is pretty dynamic right now. It's winning me a lot of points," Williams said.

In the second set, Williams saved break points in the first and seventh games.

Sharapova advanced by beating 2006 quarterfinalist Severine Bremond of France 6-0, 6-3. The 2004 champion has shown no sign of the injured right shoulder that bothered her at the French Open.

"I was able to hold my serve after getting that break in the second set, and I was able to follow through," said Sharapova, the 2004 champion.

Mauresmo, who beat Justin Henin in last year's final, easily beat Yvonne Meusburger of Austria 6-1, 6-2.

Mauresmo is seeded only No. 4 because she was sidelined following an appendectomy in March and had a groin problem that contributed to an early exit at the French Open.

French Open finalist Ana Ivanovic also advanced to the third round, beating Meilen Tu of the United States 6-4, 6-3. The sixth-seeded Serb reached the fourth round last year.

Also, No. 5 Svetlana Kuznetsova, No. 8 Anna Chakvetadze No. 10 Daniela Hantuchova, No. 11 Nadia Petrova, No. 12 Elena Dementieva and No. 14 Nicole Vaidisova won. No. 13 Dinara Safina and No. 17 Tatiana Golovin lost.

Henman was eliminated by Feliciano Lopez of Spain 7-6 (3), 7-6 (5), 3-6, 2-6, 6-1 in a match that started a day earlier. It was the third year in a row that Henman lost in the second round.

Henman, who also played five sets over two days in the first round, was the last British man or woman in the tournament. This was his 14th appearance at Wimbledon, and there has been speculation that it might be his last.

After the fourth set, the 78th-ranked Lopez took a bathroom break, which broke Henman's momentum.

"When you get into a fifth, you've got to try to maintain that momentum," Henman said. "Suddenly he hits two or three good shots in one game and he's in the driver's seat."

Henman walked to the middle of Centre Court to acknowledge a standing ovation, and then left with no emotion.

"I feel sorry for him because they (British fans) love him and support him a lot," Lopez said.

Wayne Arthurs, playing in the final tournament of his 17-year career and at 36 the oldest man in the starting draw, upset No. 11 Tommy Robredo of Spain 6-3, 7-6, (5), 6-3. Robredo is the highest seeded player to be eliminated.

Djokovic advanced by beating Amer Delic of the United States 6-3, 3-6, 6-3, 7-6 (4), while Blake defeated Andrei Pavel of Romania 6-4, 6-3, 6-3, Davydenko rallied to beat Chris Guccione of Australia 3-6, 5-7, 7-6 (5), 6-4, 6-2 and 2002 champion Lleyton Hewitt beat Simone Bolelli of Italy 6-2, 6-2, 6-1.

No. 7 Tomas Berdych, No. 13 Tommy Haas, No. 15 Ivan Ljubicic and No. 20 Juan Carlos Ferrero also won, while No. 17 David Ferrer, No. 24 Juan Ignacio Chela and No. 29 Agustin Calleri lost.