NEW YORK -- Pete Sampras loves it under the lights at the U.S. Open.

He improved his career mark to 18-0 in night matches at the year's final Grand Slam tournament by beating 85th-ranked Kristian Pless of Denmark 6-3, 7-5, 6-4 Friday to reach the third round.

"You're just a little more keen at night than during the day. At least I am,'' Sampras said. "My body's awake, and the energy's there.''

After taking a jog to work up a sweat ahead of the match, Sampras powered in 21 aces and ended it with his fastest of the night: 135 mph. He had a total of 56 winners, to just 16 unforced errors, and faced only one break point, which he saved.

Sampras is just 22-17 in 2002, having lost in the first round at the French Open and the second round at Wimbledon. He hasn't won a tournament of any sort since July 2000, when he captured Wimbledon for his record 13th Grand Slam title.

"I hit the pinnacle, and ever since then it's been tough to get going at certain places,'' he said.

That two-year drought contributed to Sampras being seeded only 17th at this year's Open. He'll next face 1997 finalist Greg Rusedski, who got past Paradorn Srichaphan 3-6, 7-6 (2), 7-6 (5), 6-7 (3), 6-4 Friday night in a 3-hour, 44-minute match that ended at midnight.

In his previous 13 Opens, Sampras has failed to get to the fourth round only once: when he lost in the first round in his 1988 debut. He's won the tournament four times and been the runner-up three, including in 2000 and 2001.

"It's the U.S. Open -- this is what I play for,'' Sampras said. "It's been a struggle this year, but hopefully I can get it going here. I feel really comfortable playing here.''

Pless has never been past the third round of any Grand Slam tournament.