Andre Agassi and Pete Sampras warmed up for their showdown at the ATP Tour World Championship with quick, straight-set victories today against South Americans.

Top-ranked Agassi beat No. 8 Nicolas Lapentti of Ecuador, 6-1, 6-2. Sampras, playing only his second match in three months, downed Gustavo Kuerten of Brazil, 6-2, 6-3.

Sampras, who has been slowed by hip and back injuries, showed no signs of rustiness in beating the world's No. 3 player in 53 minutes.

"I was pleasantly surprised the way I played, the way I moved," said Sampras, a four-time champion in the $3.6 million season-ending event. "Didn't feel my back."

The tournament brings together the world's top eight players. Under the round-robin format, Agassi next will play Sampras in the Red Group.

With the top two finishers from each of the four-player groups moving to the semifinals, the winner of Wednesday's showdown almost certainly will advance.

"It's always unique when I can step out against him, both being American and different personalities," Sampras said. "It's a great clash."

In the White Group, No. 2 Yevgeny Kafelnikov defeated No. 6 Todd Martin, 6-4, 1-6, 6-1.

Sampras dropped to No. 5 during his long layoff after finishing six straight years as No. 1.