Pete Sampras and the rest of the world's top tennis players are doing little work on this Labor Day weekend.

The top-seeded Sampras needed just 78 minutes to defeat Mikael Tillstrom 6-2, 6-3, 6-1 Saturday night to advance to the fourth round of the U.S. Open, and several of his peers spent even less time on court.Defending champion Patrick Rafter won in 66 minutes, dropping only three games in a third-round victory. Andre Agassi advanced while losing just five games. Venus Williams needed to play only half a match.

"You never feel badly about winning. You want to get on and off as quick as you possibly can," Rafter said after his 6-1, 6-1, 6-1 victory over David Nainkin. "This is a Grand Slam. You want to conserve your energy."

Only two seeded women and four seeded men have been eliminated.

Sampras, serving 14 aces at up to 125 mph, was expressionless for most of the match as he pounded winners past the Swede. But the four-time U.S. Open champion raised his arms to the crowd to solicit applause on one point after slamming a forehand down the line.

Sampras' next opponent will be unseeded Marat Safin, the Russian teenager who became a crowd favorite in Paris with his improbable run through this year's French Open. He defeated Thomas Muster in the third round.

The third-seeded Rafter, who lost just six points on his first serve and never faced a break point, will face No. 14 Goran Ivanisevic in the fourth round.

Ivanisevic had 21 aces in a 7-6 (7-5), 6-3, 6-4 win over Paul Haarhuis, a player who had tormented him in the past. The temperamental Ivan-i-se-vic said he has been playing better since banging his head on the court during a second-round win over Todd Martin earlier this week.

"Sometimes I am a little bit messed up," he explained. "I have to bang, then everything comes together."

Agassi won 6-2, 6-3, 6-0 in 96 minutes over Davide Sanguinetti, who twisted his right ankle late in the first set and played the rest of the match with the ankle heavily taped. Agassi's next opponent will be No. 9 Karol Kucera.

The only men's seed to lose Saturday was No. 6 Greg Rusedski, who was upset 4-6, 6-4, 5-7, 6-2, 6-4 by Jan Siemerink in a match that lasted 3 hours, 22 minutes. Rusedski was a U.S. Open finalist last year.

Williams' match lasted just 13 minutes. She was leading 5-0 in the first set when Larisa Neiland retired because of a painful lower back injury.

Neiland was unable to move more than a few feet from the middle of the court, watching helplessly when Williams hit shots into the corners. Neiland's face was contorted with pain as she held onto the umpire's chair for support after five games and told Williams she could not continue.

"I really would have enjoyed to have a match where she could have played to her full ability," Williams said. "I can get the preparation on the practice court."

Agassi, who played third on the Arthur Ashe Stadium court after Rafter and Williams, was shocked to start playing so early in the afternoon.

"Both matches combined were like an hour and 15 minutes, phenomenal," Agassi said. "I felt rather rushed, I didn't enjoy that at all."

Women's winners included No. 2 Lindsay Davenport, No. 4 Arantxa Sanchez Vicario, No. 7 Conchita Martinez, No. 10 Nathalie Tauziat, No. 12 Mary Pierce, No. 13 Amanda Coetzer and No. 15 Anna Kournikova.

Fourteen of the 16 women's seeds reached the fourth round, the first time that has happened since 1987. And the ease with which favorites are advancing is in stark contrast to this year's French Open and Wimbledon, in which there were many surprises.

"It's been weird because the other Grand Slams, there's been a lot of upsets, a lot of seeds that haven't made it," Davenport said. "I don't know what the reason is, but it just seems like the players who are expected to win so far are winning."