SAN JOSE, Calif. -- Unseeded Croatian Ivo Karlovic upset second-seeded American James Blake 6-7 (4), 7-6 (11), 6-4 to advance to the quarterfinals of the SAP Open on Thursday.
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The 6-foot-10 Croatian, who's ranked 103rd in the world, used 29 aces to beat the sixth-ranked Blake. Karlovic saved five match points in the second tiebreaker.
Top-seeded Andy Roddick defeated wild-card Sam Querrey 6-4, 7-6 (3) to advance to the quarterfinals.
Blake had Karlovic down 30-love in the second set while leading 5-4, but Karlovic came back to tie the match 5-5 and win it in the tiebreaker.
"After I lost my serve, I knew that it was my only chance to break him and win the set," Karlovic said. "After I won the set, I felt really up. And felt my playing level go up."
After taking the set, Karlovic began to attack Blake's game instead of relying on his booming serve, which was clocked at more than 140 mph.
"After winning the second set, I became more aggressive in going after his serve and I felt more confident on the court," Karlovic said.
Karlovic is coming off a left knee injury last year. He faces fifth-seeded Mardy Fish, who defeated Sam Warburg 2-6, 6-4, 6-2.
"It's disappointing to lose," Blake said. "There's no one to blame but myself for the errors I made out there. I couldn't make a first serve. I had few match points to get and I couldn't close him out.
Blake had trouble dealing with Karlovic's height and service.
"I wasn't used to dealing with the angle it was coming in," Blake said. "I see a lot of big serves dealing with Andy [Roddick]. But you don't see anyone coming from 6-foot-10. I felt I got on it well enough to win, but I didn't take advantage of him when I need to."
Roddick, the fourth-ranked player in the world, improved his SAP Open record to 19-3, but had trouble with his serve all night, delivering just 11 aces.
"Two years ago, I feel like Sam was an after-school tennis player," said Roddick, who trains with Querry. "Now he's playing with great stuff and I think he's learning every day. He's not going to get blown out a lot."
Querry stayed alive by serving 20 aces, but was done in when Roddick converted on triple match point during the tiebreaker.
Roddick will face eighth-seeded Vincent Spadea in the quarterfinals.
Fourth-seeded Marat Safin of Russia also advanced when he defeated unseeded Lu Yen-hsun of Chinese Taipei 6-4, 5-7, 6-4. Safin is ranked 25th in the world and Yen-hsun is 93rd.
"I had a hard time out there," Safin said. "He doesn't make many unforced errors, I just had to rely on my experience to beat him."
Safin, who is playing in his first SAP Open, faces Germany's Benjamin Becker in the quarterfinals.
Earlier Thursday, Hyung-Taik Lee, Becker and Spadea also reached the quarterfinals.
Lee beat Simon Greul 6-2, 7-6, Becker downed Bjorn Phau 7-6, 1-6, 6-3 and Spadea outlasted Feliciano Lopez 4-6, 7-5, 7-6.
The quarterfinals will also feature Lee against defending champion Andy Murray.
Copyright 2007 by The Associated Press
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