Walking off the court after upsetting third-seeded Tim Henman, Jan Kroslak pumped both fists into the air and erupted in a guttural scream. His response to his 3-6, 6-3, 6-4 victory was hardly unexpected. The 24-year-old Slovakian, ranked No. 71, never had beaten a top 10 player until last night at the Legg Mason Tennis Classic.

"I was just playing my game," Kroslak said. "I saw that he doesn't like it."

Coming into this tournament, Kroslak had lost 13 of his last 20 ATP Tour matches -- including six straight in the opening round -- but was 2-0 against Henman. He beat him in 1995 in a Davis Cup match and this year at an indoor tournament in London, but Kroslak said he couldn't explain his success against Henman.

"It's always some players who don't like the game that [the lower-ranked player is] playing, so they can't beat them," Kroslak said. "I'm 0-4 against Martin Damm. I can't beat him. I don't know why."

Kroslak's game plan was to make the match an endurance contest. So rather than go for a quick winner, he would drag out each point.

"I knew he was not in good shape," Kroslak said. "I wanted to keep the ball in play as long as possible."

Henman has been in a slight slump lately, losing five of his last eight matches. A strong grass court player, Henman has never been particularly fond of the hard court. He is 15-10 this year on that surface. He had hoped to use this tournament as a preparation for the U.S. Open.

"It's frustrating," Henman said. "I never really established my authority in the second set. He seems to get better as the match goes on."

No. 135 Zib in Quarterfinals

One of the surprising quarterfinalists is Tomas Zib, a 23-year-old from the Czech Republic. The 135th-ranked Zib, who had won just one ATP Tour match in his career before this tournament, defeated Switzerland's Marc Rosset, 6-3, 6-2. Zib's only other win was last April when he beat Marat Safin at the Czech Open in Prague. Since turning professional in 1995, he has played just four ATP Tour events.

"This is one of the biggest wins," said a dazed and happy Zib. "I had nothing to lose. I was trying to play my best."

Zib meets Yevgeny Kafelnikov, a 7-5, 6-4 winner over Justin Gimelstob, in the next round. The two have played each other once before, in an Italian junior tournament.

"I have nothing to lose," Zib said. "He's a big star now."

Stolle, Black Notch Win

Sandon Stolle and partner Wayne Black defeated Lucas Arnold and Eyal Ran, 6-3, 6-3, in their first match. The top-seeded pair, who have won three ATP Tour doubles titles this year, had a first-round bye. . . .

Todd Martin advanced to the quarterfinals in a walk-over when Paraguay's Ramon Delgado withdrew from their scheduled match. Delgado, who defeated Michael Chang, 6-4, 1-6, 6-3, on Wednesday, sprained his left ankle during practice yesterday morning.