New York ? Robby Ginepri, an unsung, unseeded American toiling hard through the U.S. Open, has reached a Grand Slam semifinal for the first time.

Ginepri gutted his way out of trouble and upended Guillermo Coria, 4-6, 6-1, 7-5, 3-6, 7-5, Wednesday.

Ginepri’s semifinal foe Saturday will be Andre Agassi, a five-set winner over James Blake in the late night match.

Agassi lost the first two sets, 3-6, 3-6, then won, 6-3, 6-3, 7-6 (6), in a match that ended after 1 a.m. Eastern time.

“The last three matches took so much out of me, I’m just dead right now,” Ginepri told the crowd as his family, suffering and celebrating on alternate points, watched from the players’ box. His sister, Jenni, took photos as he spoke. “I don’t know how I got through that match.

“I don’t know what’s going on right now. I’m a little foggy, a little dizzy. It’s crazy. Crazy!”

Almost as crazy was top-ranked Lindsay Davenport, the 1998 champion, getting thumped in the first set by last year’s finalist, sixth-seeded Elena Dementieva, and losing a match of epic sloppiness, 6-1, 3-6, 7-6 (6).

“It seems like a lucky place for me,” said Dementieva, who overcame 12 double-faults and had 43 unforced errors to Davenport’s 56. “After last year, I’m still dreaming about Saturday night every single day, so who knows?”

Dementieva will play Friday against No. 12 Mary Pierce, the 2000 French Open and 1995 Australian winner who advanced to her first U.S. Open semifinals by beating fellow Frenchwoman Amelie Mauresmo, 6-4, 6-1.

“It’s amazing,” said Pierce, who reached the French Open final in June. “I’m 30, 17th year on the tour, and there’s still firsts for me. That’s pretty exciting.”

Down a break in the fifth set, Ginepri beat the No. 8 Coria, the Argentine who was a French Open finalist last year, in a match that took just over three hours and ended with a dramatic series of six match points.

Ginepri has had only a few claims to fame so far – his second career title at Indianapolis in July, where he beat Andy Roddick in the quarters and Taylor Dent in the final; a semifinal finish in Cincinnati last month, where he gave No. 1 Roger Federer a tough, three-set match.

Oh, yes, he also dated actress Minnie Driver a couple of years ago.

“I hope I’m more notable for my tennis than being with her,” he said.