PARIS -- No. 5 Roger Federer and No. 10 Paradorn Srichaphan became the two early upset victims at the French Open on Monday.

Federer, a favorite to win the title, was ousted in the opening round for the second straight year, committing 82 unforced errors and losing to Peru's Luis Horna 7-6 (6), 6-2, 7-6 (3). Horna, the 1997 juniors runner-up at Roland Garros, had never previously won a Grand Slam match.

"It's a big disappointment,'' Federer said. "Very sad to leave so early. I should have played better.''

Horna, the 1997 juniors runner-up at Roland Garros, had never previously won a Grand Slam match.

"This is the most wonderful feeling I've ever had throughout my life,'' he said. "The fact that I was going to play Federer the first round, I was a bit nervous.''

Paradorn was eliminated by Dominik Hrbaty 6-4, 3-6, 6-0, 7-5.

Andre Agassi, the 1999 champion, double-faulted twice on match point before finishing off Karol Beck 6-2, 6-3, 6-3.

"I'm here because I believe I can win,'' said Agassi, at 33 the oldest player in the men's draw. "I've still got a chance.''

James Blake won a showdown of young Americans, beating Taylor Dent 6-4, 6-3, 7-6 (3). Carlos Moya, the 1998 champion, beat Filippo Volandri 7-6 (7), 4-6, 6-2, 6-3. American Vince Spadea outlasted Irakli Labadze 6-1, 3-6, 5-7, 6-4, 6-1. Mark Philippoussis rallied past American qualifier Alex Kim 2-6, 6-7 (1), 7-5, 6-2, 6-2.

Defending men's champion Albert Costa opens Tuesday against lucky loser Sergio Roitman.

The French Open is the only title for Costa in his past 88 events, dating to August 1999. He has won just three Grand Slam matches since his remarkable showing at Roland Garros, which included an upset of three-time champion Gustavo Kuerten and a win over Spanish compatriot Juan Carlos Ferrero for the title.

With 15 wins and 11 losses this year, including a modest 7-5 record on the clay surface he prefers, Costa again begins the tournament as a long shot. While he acknowledged that he's not playing as well as at the start of the tournament a year ago, he said he's more relaxed.

"I don't know if the people think I'm not going to repeat,'' he said Sunday. "I don't mind.''

But it would be wrong to discount Costa as a title contender in the most unpredictable of major events -- for men, anyway.

More than a dozen players, including a handful of Argentines and Spaniards, can claim a legitimate shot at the men's trophy. Costa puts the number at about 20, and history supports his contention that the draw is wide open.

Like Costa, Michael Chang (1989), Andres Gomez (1990), Thomas Muster (1995) and Carlos Moya (1998) won their only major title in the French. Eight men's champions at Roland Garros since 1983 have failed to duplicate that success at another Grand Slam event -- the Australian Open, Wimbledon or the U.S. Open.