BEIJING — Rafael Nadal advanced Wednesday into the quarterfinals at the Olympics, digging out of a hole in a pivotal service game and beating Igor Andreev of Russia, 6-4, 6-2.

The No. 2-seeded Nadal is seeking his first Olympic tennis medal to complement the French Open and Wimbledon titles he has won this year.

No. 3 Novak Djokovic, who could meet Nadal in the semifinals, beat No. 13 Mikhail Youzhny of Russia 7-6 (3), 6-3.

Venus Williams, playing her first tournament since winning Wimbledon for the fifth time, reached the quarterfinals by beating No. 12 Victoria Azarenka of Belarus 6-3, 6-2. Williams, seeded seventh, is seeking to add to her medal collection after winning the singles and doubles at Sydney in 2000.

Nadal played his third-round match on Court 1, which resembles a bull ring, and the Spaniard looked right at home as he wore down Andreev from the baseline. The 4,000-seat stadium was packed, and because of heavy haze the lights were on despite a 4 p.m. start.

Nadal broke for a 4-3 lead and served for the first set three games later. He fell behind love-40 and faced four break points in the game but overcame them all, with Andreev hitting a service return out each time.

In the second set, Nadal raced to a 4-0 lead. He closed out the match with a service winner, then punched the air in triumph.

Nadal is assured of climbing to No. 1 in the rankings next week, ending Roger Federer's 4 1/2-year reign.

Federer was scheduled to play Wednesday night. He could meet Nadal for the gold medal Sunday in a rematch of their epic Wimbledon final.

On the women's side, new No. 1 Jelena Jankovic and Venus and Serena Williams had matches scheduled later Wednesday.