WIMBLEDON, England ? Defending champion Roger Federer overcame 2002 winner Lleyton Hewitt in four sets Wednesday to reach the Wimbledon semifinals, edging closer to a possible final against Andy Roddick.

Federer lost his serve and dropped a set for the first time this tournament, but had 19 aces and 50 winners to prevail, 6-1, 6-7 (1), 6-0, 6-4, in a high-quality Centre Court match that ended close to dusk. It was Federer’s 22nd consecutive win on grass.

The 2-hour, 19-minute match ended with a double-fault by Hewitt.

Roddick, who hasn’t lost a set in five matches, served 18 aces and outslugged Sjeng Schalken, 7-6 (4), 7-6 (9), 6-3 — closing out the match with a leaping overhead.

The second-seeded Roddick advances to meet Croatia’s 20-year-old Mario Ancic, who defeated fifth-seeded Tim Henman, 7-6 (5), 6-4, 6-2. Roddick is 1-0 against Ancic, winning in three sets on grass at Queen’s Club last month.

Federer will face Sebastian Grosjean, who swept Florian Mayer, 7-5, 6-4, 6-2 to reach the semis for the second straight year.

In women’s play, two-time defending champion Serena Williams beat a listless Jennifer Capriati, 6-1, 6-1, in 45 minutes in a Centre Court match that never lived up to expectations. Williams goes next against Amelie Mauresmo, who beat Paola Suarez, 6-0, 5-7, 6-1 to make her second Wimbledon semifinal.

The Federer-Hewitt match, interrupted twice by rain for about an hour each time, featured a contrast between the all-court Swiss player with a big serve and the hustling Australian baseliner with a fantastic return.

“It was a battle where I really had to run a lot,” Federer said. “The first and third sets don’t show how hard the battle was.”