-- It was after midnight that 35-year-old Andre Agassi came alive.

Playing an opponent 10 years his junior before a raucous crowd at the National Tennis Center, Agassi roared back from a two-set deficit early Thursday morning to defeat fellow American James Blake, 3-6, 3-6, 6-3, 6-3, 7-6 (8-6), and advance to the semifinals of the U.S. Open.

The 2-hour 51-minute match stretched past 1 a.m. and thrilled the roughly 20,000 spectators who stayed until the end. Agassi and Blake rewarded them with exceptional shot-making and heart, endearing themselves further to a crowd that long ago had surrendered its heart -- to Agassi, for the effort and excellence he continues to bring to the sport after his peers have long since retired; and to Blake, whose comeback from injury, illness and loss has inspired fans and non-fans of the sport alike.

Fittingly, the match ended on Agassi's signature shot -- a serve return winner. And when they met at the net, Agassi offered a handshake and warm embrace, and Blake offered the same, saying, "It couldn't have been more fun to lose."

Blake had exceeded all expectations, as well as his wildest dreams, since he arrived at the National Tennis Center for his fifth U.S. Open. And with each round, he has won fans along the way.

Wednesday night, with Agassi's serve failing him in the early going, Blake broke his idol four times to take a 6-3, 6-3 lead and carried that momentum into the third set.

Down a break, Agassi broke back and held for a 4-3 lead. His resurgence thrilled the crowd and rattled Blake. He dropped his serve in an error-plagued game to hand Agassi a 5-3 lead. And the grandstands erupted, not because fans had taken sides but because they clamored for more. Agassi clinched the set to gave them just that.

Finally loose, he rolled through the fourth set as midnight came and went.

Blake got the first break in the fifth set with a forehand return winner to take a 3-2 lead. From there, it was up to Agassi to break back. To a wild soundtrack of "Andre! Andre!" he pulled even at 5-5. And a tiebreaker settled it, ending at 1:10 a.m.

"I wasn't the winner," Agassi told the cheering throng at Arthur Ashe Stadium. "Tennis was."

It was a thrilling finale to a day that saw top-ranked Lindsay Davenport bounced by last year's runner-up, Elena Dementieva, who overcame 12 double faults en route to a 6-1, 3-6, 7-6 (8-6) victory. The result means that for the first time since 1994, there won't be an American woman among the U.S. Open's women's semifinalists.

Dementieva's semifinal opponent will be 30-year-old Mary Pierce, who continued her career renaissance with a 6-4, 6-1 romp over third-seeded Amelie Mauresmo.

In the men's draw, unseeded Robby Ginepri advanced to his first grand Slam semifinal by upsetting eighth-seeded Guillermo Coria of Argentina, 4-6, 6-1, 7-5, 3-6, 7-5. His reward: a date with Agassi.

The 29-year-old Davenport, competing in her 15th consecutive U.S. Open, breezed through her first four rounds without dropping a set. There was little reason to think she would break stride against the sixth-seeded Dementieva, known for the power of her forehand and the crippling inefficiency of her serve -- a liability of such magnitude that it's a marvel she has earned a spot among the top 10.

But the Davenport who walked onto court bore no resemblance to the player who has carved such a prominent place in the game's record books. She lost her serve -- at 6 feet 21/2, it is her chief weapon -- four games in a row in the opening set. And her groundstrokes lacked pace and precision.

"I felt like for a while there I couldn't have played much worse," Davenport conceded, "It was not good."

Davenport's 56 errors (to 24 winners) made for a miserable statistic. But Dementieva, she pointed out, had a lot to do with it. "She's a huge fighter," Davenport said. "She manages to stay positive in some very bizarre circumstances in matches."

Ginepri had an even tougher time on court, forced into his third consecutive five-set match of the tournament -- enough to leave him as dazed as a boxer on the ropes. "The last three matches took so much out of me, I'm just dead right now," Ginepri mumbled to the crowd at Arthur Ashe Stadium, too depleted to mount the perfunctory display of postmatch euphoria for the TV cameras zooming in on his blank face.

The match wasn't just long; it was mentally wrenching, with Ginepri failing to convert five match points before the indefatigable Coria double-faulted for a 14th time to put the contest out of its misery.

The moral was clear: Form is nice, and fitness definitely helps; but when all else is equal on a tennis court, what's between the ears -- the ability to handle pressure, maintain focus and stay positive -- is what matters most. And that's what Ginepri kept reminding himself each time Coria nudged ahead.

"Just tried to stay calm, stay focused, and get back to what I do best, which is get the ball in play and go for my shots when it's there," said Ginepri, 22. "Match isn't over until it's over."

Also Wednesday Paul Goldstein of Rockville and doubles partner Jim Thomas fell to the second-seeded Bryan twins in semifinal action, 3-6, 6-1, 6-2. In women's doubles, 48-year-old Martina Navratilova and Anna-Lena Groenefeld upset Svetlana Kuznetsova-Alicia Molik, 6-7 (7-5), 7-5, 7-5, to advance to the semifinals.

James Blake, above, wins the first two sets, 6-3, 6-3, but can't put away Andre Agassi, who won the final 3 sets, 6-3, 6-3, 7-6 (8-6). "It couldn't have been more fun to lose," Blake said.Seventh-seeded Andre Agassi celebrates his victory, which took 2 hours 51 minutes. "I wasn't the winner," Agassi told the cheering throng at Arthur Ashe Stadium. "Tennis was."