WIMBLEDON, England -- Andre Agassi broke serve only once but played two nearly flawless tiebreakers Saturday to edge Younes El Aynaoui 5-7, 6-4, 7-6 (4), 7-6 (4) in the third round at Wimbledon.

Agassi, trying at 33 to become the oldest Wimbledon champion in the Open era, will face another big server in the fourth round Monday -- Mark Philippoussis.

El Aynaoui hit 19 aces to keep every set close, and three times he was within one point of forcing a fifth set.

''So much does boil down to his serve,'' Agassi said. ''It was so important today for me to take care of my own serve. So I felt very, very focused.''

In women's play, surprising 16-year-old Maria Sharapova notched her biggest win yet at Wimbledon, upsetting 2000 semifinalist Jelena Dokic 6-4, 6-4.

Also advancing were three other Russians -- No. 10 Anatasia Myskina, No. 15 Elena Dementieva and Svetlana Kuznetsova -- to give their country five women in the final 16. That's a Grand Slam record for Russia.

Defending champion Serena Williams, French Open champion Justine Henin-Hardenne and Jennifer Capriati won in straight sets.

On the men's side, French Open champ Juan Carlos Ferrero, 2002 runner-up David Nalbandian and No. 10 Tim Henman advanced. Henman is trying to become the first Englishman to win Wimbledon since 1936.

Agassi erased three set points serving at 5-6, 0-40 in the fourth set, and he came up with clutch shots in both tiebreakers, including a forehand winner on his final swing to close the 3-hour, 13-minute match.

The No. 2-seeded Agassi lost serve only once and changed his usual tactics by occasionally playing serve and volley. He won 27 of 30 points at the net.

''I don't know what got into me there,'' Agassi said. ''I probably won't do that again until about 2010.''

Philippoussis, a three-time quarterfinalist but unseeded, fired 33 aces and defeated No. 35 Radek Stepanek 4-6, 7-6 (7), 6-4, 7-6 (6). Agassi has beaten Philippoussis in six of their seven matches, including their only meeting on grass in the 2000 quarterfinals at Wimbledon.

Williams beat fellow American Laura Granville 6-3, 6-1 and will next play Dementieva. Henin-Hardenne, seeded third, beat Alicia Molik 6-4, 6-4.

Capriati, seeded eighth, requested treatment on her right shoulder from a trainer during the first set but still beat Akiko Morigami 6-4, 6-4.

Myskina was a 6-3, 6-3 winner against 1994 champion Conchita Martinez, who was seeded 18th. Dementieva beat Aniko Kapros 6-3, 6-1.

Two-time Grand Slam champion Mary Pierce eliminated No. 23 Lisa Raymond 4-6, 6-3, 7-5.

The No. 3-seeded Ferrero defeated Sargis Sargsian 6-4, 6-4, 2-6, 6-4. Nalbandian, seeded sixth, stopped Karol Kucera 6-4, 5-7, 6-7 (1), 6-4, 6-2. Henman swept 18-year-old Swedish qualifier Robin Soderling 6-3, 6-1, 6-4.

Olivier Rochus reached the fourth round at a Grand Slam event for the first time by beating No. 30-seeded Jarkko Nieminen 7-6 (5), 6-3, 6-1. Alexander Popp of Germany, a quarterfinalist in 2000, downed No. 11 Jiri Novak 6-3, 6-4, 7-6 (3).

Popp's mother is English, and the London media are eager to adopt him as British -- during Wimbledon, at least.

''Well, it's up to you,'' Popp said. ''But obviously I've been playing for Germany the last 26 years, and it doesn't look like it's going to change.''