WIMBLEDON, England (AP) — Roger Federer endured two rain delays and a shaky moment late in the first set Wednesday to reach the quarterfinals at the Olympics by beating Denis Istomin of Uzbekistan 7-5, 6-3.

Serving at 5-all in the first set, the No. 1-seeded Federer faced three break points and erased them all. He then broke and was in control from there.

A fourth-time Olympian, Federer has yet to win a career singles medal, although he and Swiss teammate Stanislas Wawrinka did win the gold in doubles in 2008. Federer's playing his first tournament since winning a record-tying seventh Wimbledon title.