Andre Agassi came out, fluffed two backhands, clipped the net cord with a faulty forehand, and double-faulted. Everything went downhill from there.

It is unwise to offer a game start to a clay-courter of Alberto Costa's standard, and Agassi's unhappy association with the Monte Carlo Open continued with a 54-minute trouncing by the Spaniard, 6-2, 6-1.

Boris Becker, whose frustrated quest for a title on clay has ended in three finals here, quickly followed Agassi out of the tournament, outplayed 6-4, 6-3, by Marcelo Rios, whose victory guaranteed the impressive Chilean left-hander's promotion to the world's top 10.

The casualty rate has been so high that Rios, seeded No 13, is one of only three seeds to advance to today's quarter-finals. Costa is No 16. The other is Thomas Muster, the No 1 seed and defending champion. It is possible that Muster and Rios will meet in the final, as they did in Barcelona last Sunday, when Muster won in four sets.

Spectators responded sympathetically to Becker's plight, remembering that he had two match points against Muster in last year's final and has lost valuable court time of late because of bronchitis. But the crowd booed and whistled Agassi's performance, wondering how someone who has twice been runner-up at the French Open could appear so hapless.

"Yeah, they were almost as disappointed as me," Agassi said. "You go out there and you try. You get your ass kicked. They expect you to do well. They want you to win. It's disappointing.''

That has been a recurring story for Agassi in Monte Carlo. At least on this, his third visit, the No 2 seed managed to win a match, defeating the Dutchman Jan Siemerink in straight sets.

Yesterday's dark clouds, damp courts and generally heavy conditions foretold of difficulties for the unprepared. The No 26-ranked Costa, playing Agassi for the first time, clamped his will on an opponent whose returns yielded only two break points, neither of which was converted, and whose percentage of first serves was as low as 38.

"I saw he was making mistakes and was not feeling good on the court, and this gave me confidence," Costa said. "In the end of the rally, he finally missed the ball himself.''

The 20-year-old Rios reasoned that he had a chance of beating Becker from the baseline if he did not become over-ambitious in attempting to return the No 4 seed's booming serves. His patience was rewarded.

Becker predicted that Rios's fame would quickly spread beyond Chile, where he is already a national sporting hero. "He deserves to be in the top 10," Becker said. "He's a player who has a gifted hand and good vision. I don't think he actually considers himself a clay-court specialist. I think he prefers slow hard court. But it shows his talent that he can play on a very wet clay court.

"He's a very good counter-puncher. He plays with the power of the other guy, takes the ball early, and has a very good feel for the court. On a good day, he can be excellent. The surface doesn't matter. He has a good eye for everything.''

QUARTER-FINAL LINE-UP: Thomas Muster (Aut) v Sjeng Schalken (Neth); Carlos Costa (Sp) v Cedric Pioline (Fr); Magnus Gustafsson (Swe) v Marcelo Rios (Chile); Felix Mantilla (Sp) v Alberto Costa (Sp).