American Serena Williams advanced to the fourth round of Wimbledon following a victory over Italian Roberta Vinci on Friday. (Sang Tan/Associated Press)

Roger Federer and Serena Williams, both looking to regain Wimbledon titles, advanced to the fourth round of the tournament with victories on Friday.

Federer dropped his first set this week but then righted the ship to defeat Philipp Kohlschreiber of Germany 6-3, 6-2, 6-7 (5), 6-1. The Swiss star and top seed is looking for his sixth Wimbledon title and a record 15th Grand Slam win overall.

"It has been a good first week," he said. "Pretty convincing. I thought this was my best match of the tournament, even though I dropped a set. I'm excited about the second week."

Federer will next face the man he blitzed in the French Open final earlier this month, Robin Soderling. The Swede won 7-6 (7), 6-4, 6-4 over Nicolas Almagro of Spain.

Williams stayed on course for a third tournament crown with a 6-3, 6-4 win over Roberta Vinci of Italy. The American lost in the final last year to sister Venus.

"I don't think I played great today at all," Williams said. "I'm just glad to have gotten through it and go on to the next match."

Williams will next meet Daniela Hantuchova. The tall Slovakian set aside Japanese veteran Ai Sugiyama 6-4, 6-3.

Two matches were suspended just after 9:30 in London due to darkness. Tommy Haas of Germany and Marin Cilic of Croatia were knotted 6-6 in the fifth and deciding set, while Russian Igor Andreev was up 2-1 in sets with a 5-5 score in the fourth against Italy's Andreas Seppi.

Top French players fall

Russian seeds Elena Dementieva and Nadia Petrova also advanced on Friday. No. 4 Dementieva beat compatriot Regina Kulikova 6-1, 6-2, while the 10th-seeded Petrova was a 3-6, 6-3, 6-4 victor over Gisela Dulko of Argentina. Dulko had upset former champion Maria Sharapova earlier in the week.

Dementieva goes on to meet fellow Russian Elena Vesnina, who scored a mild upset over No. 14 Dominika Cibulkova of Slovakia 7-5, 4-6, 6-4.

Petrova draws teen Victoria Azarenka of Belarus. The No. 8 seed Azarenka topped Romania's Sorana Cirstea 7-6 (2), 6-3.

Marion Bartoli, the 2007 Wimbledon finalist, was eliminated. Francesca Schiavone of Italy dispatched the No. 12 seed from France, 7-6 (5), 6-4. Schiavone earlier in the week defeated Canadian Aleksandra Wozniak.

No. 26 Virginie Razzano of France caught a break when No. 7 Vera Zvonareva of Russia pulled out of their match because of injury.

In other men's action, No. 4 Novak Djokovic of Serbia put up a 6-4 score in all three sets against American Mardy Fish. Djokovic in the fourth round will play Israel's Dudi Sela, who upset No. 15 Tommy Robredo of Spain 7-6 (8), 7-5, 2-6, 7-5.

Ivo Karlovic of Croatia pulled off a minor upset over No. 9 seed Jo-Wilfried Tsonga of France. The six-foot-nine-inch Karlovic, seeded 22nd, won by scores of 7-6 (5), 6-7 (5), 7-5, 7-6 (5).

The Croatian fired a whopping 46 aces in the win.

Karlovic will meet No. 7 Fernando Verdasco of Spain. Verdasco beat countryman Albert Montanes 4-6, 6-1, 6-4, 7-6 (2).

With files from The Associated Press