BEIJING (AP) – Roger Federer directed an angry scream toward his feet. He swatted a stray ball in frustration. He slapped his thigh, hung his head and stomped behind the baseline.

And finally, he questioned calls, something he hates to do. That merely made him madder: He went 0-4 on replay challenges.

For Federer, it was that kind of night. It has been that kind of year.

Federer’s long slump continued and the bid for his first Olympic singles medal ended Thursday when he lost to American James Blake.

So began an upset parade in the quarterfinals. Serena Williams lost to Elena Dementieva of Russia, and as the clock approached midnight, Venus Williams was beaten by Li Na of China.

Matches were delayed 3 hours, 35 minutes at the start because of rain, pushing back the schedule. With four matches still in progress and top-ranked Jelena Jankovic about to begin against Dinara Safina, rain at 1:15 a.m. forced a halt until Friday.

The sequence of surprising results came in a tournament that had gone mostly according to form through three rounds. But upsets have long been the norm in Olympic tennis – since 1988, no top-five player has won the gold medal in men’s singles.

Federer won’t do it this year. With the sort of lackluster performance once unthinkable for the stylish Swiss, he was eliminated 6-4, 7-6 (2).

The No. 5-seeded Dementieva, who won a silver medal in Sydney in 2000, raced to a 5-0 lead in the final set and held on to beat Serena Williams 3-6, 6-4, 6-3. The unseeded Li then delighted a partisan center-court crowd by eliminating Venus Williams 7-5, 7-5.

A few contrarians went against the upset trend. No. 2 Rafael Nadal beat the rain and Jurgen Melzer, 6-0, 6-4, in a match that ended at 1:08 a.m. Nadal’s semifinal opponent will be No. 3 Novak Djokovic, who rallied to defeat Gael Monfils 4-6, 6-1, 6-4.

Top-seeded Mike and Bob Bryan of the United States won their quarterfinal match in doubles against Lleyton Hewitt and Chris Guccione of Australia, 6-4, 6-3.

Blake’s semifinal opponent will be No. 12 Fernando Gonzalez of Chile, who defeated Paul-Henri Mathieu of France 6-4, 6-4.

The No. 8-seeded Blake, a first-time Olympian at 28, was the lone U.S. male to survive the first round of singles. He had won only a single set in eight previous matches against Federer.

“If you play him enough times, he’s bound to have an off day,” Blake said. “I proved that I played with the best tonight, and it couldn’t have happened to me on a better stage.”

But the top-seeded Federer has been stalled all year at 12 major titles, two shy of Pete Sampras’ record. His Wimbledon reign ended last month, and he came to Beijing knowing he would lose the No. 1 ranking to Nadal next week after 41/2 years on top.

“It was one of the goals of the season for me to do well here,” Federer said. “This obviously is a big blow, because I expected more.”

Federer said he may have made a mistake this year by playing too much and not practicing enough. But he blamed his latest defeat largely on Blake.

“I’ve played him on many occasions, but I think this was the best I’ve seen him,” Federer said. “I’m happy for him. He’s a good guy. I hope he can go all the way now.”

The elimination of Federer means no rematch in Sunday’s final against Nadal, who won in epic fashion when they met for the Wimbledon title. There will be no rematch of the Wimbledon final between the Williams sisters for a gold medal, either.

No. 4-seeded Serena struggled with her serve early against Dementieva, then staged a rally in the final set. Williams overcame two match points during an 18-point game to hold for 5-3.

But Dementieva held at love in the next game, sealing the victory when Williams pushed a volley wide. The loss came after the U.S. team had won 12 consecutive matches over the past three days.

“There’s no reason I should have lost,” Williams said. “I missed some key shots that I probably shouldn’t have missed. That was that.”

A wayward forehand and 12 double-faults doomed Venus Williams. The reigning Wimbledon champion sent a forehand long to lose the serve and fall behind 6-5 in the second set, then had three more forehand errors in the final game against Li.

“She played the match of her life,” Williams said. “Not much I could do about it. So it was definitely a surprise result for me.”

The Williamses remain in the race for doubles medals. The sisters won a gold in doubles in 2000 in Sydney, and Venus also won the gold there in singles.

Federer is seeking his first medal after losing in the singles semifinals in Sydney and in the second round in Athens. He remains in contention in doubles with Swiss partner Stanislas Wawrinka.

Federer seemed off his game from the start. His forehand – once the sport’s most feared – was unreliable, and he repeatedly struggled to hold serve.

Blake earned the first break in the final game of the opening set. On set point, Federer left his feet for a spectacular backhand save that extended the rally, but with his next shot he floated an easy backhand into the net.

His shoulders sagging, he was broken again two games later and fell behind 3-0 in the second set.

Federer finally showed life by breaking back in the fifth game and holding the rest of the way to reach 6-all. But Blake played a flawless tiebreaker, while Federer made two unforced errors and popped up a volley.

When Federer sailed a return long on match point, Blake screamed “Yeah!” Federer ripped off his headband and walked head down to the net.

“In a lot of the other matches, it has been a point here or there,” Blake said. “That’s why he was No. 1 in the world – he played those points better than everyone. Today I played them well.”

AP-ES-08-14-08 1435EDT