London Olympics: U.S.’ Venus Williams loses, but John Isner wins

John Isner stayed in the hunt for a medal for the U.S. tennis team in the Olympics at Wimbledon on Wednesday, but next up is No. 1 Roger Federer.

Isner, the only remaining U.S. man in the draw, got into yet another long duel at Wimbledon, winning this time over Janko Tipsarevic of Serbia, 7-5, 7-6 (14). His match with Federer will be a quarterfinal.

Another U.S. player, Venus Williams, a gold-medal winner in three Olympics — twice in women’s doubles and once in singles — lost to Germany’s Angelique Kerber in two tiebreakers, with an identical 7-5 tiebreaker score in each.

PHOTOS: Tennis at the London Olympics

The defense of the men’s doubles gold medal was lost when Federer and Swiss teammate Stan Wawrinka were knocked out by Andy Ram and Jonathan Erlich of Israel, after a 6-1 start in the first set. The scores were 1-6, 7-6 (5), 6-3.

Two main challengers to Federer struggled, but survived.

Second-seeded Novak Djokovic got a battle from Aussie grass court veteran Lleyton Hewitt — he won the Wimbledon title in 2002 — but the Serb recovered to win, 4-6, 7-5, 6-1. Third-seeded Andy Murray, still carrying the tennis hopes of all of England after his near miss three weeks ago at Wimbledon, beat Marcos Baghdatis of Cyprus, 4-6, 6-1, 6-4.

PHOTOS: London Olympics, Day 5

Maria Sharapova, playing for Russia and seeded third, also struggled, but ended up outlasting Sabine Lisicki of Germany, 6-7 (8), 6-4, 6-3. The women’s top-seeded player, Victoria Azarenka of Belarus, got past veteran Russian Nadia Petrova, 7-6 (6), 6-4.

bill.dwyre@latimes.com