Andre Agassi fought off a match-point and a spirited effort by Belarussian Vladimir Voltchkov to book his spot in the semi-finals of the San Jose Open after a 6-7, 7-6, 6-1 victory on Friday.
The top seed will face compatriot James Blake, a 7-5, 6-2 winner over Russian Nikolay Davydenko. Sixth seed Davide Sanguinetti of Italy and unseeded American Justin Gimelstob also powered through to the last four.
Sanguinetti overcame American Vince Spadea 6-1, 7-5 while Gimelstob upset eighth seed Kenneth Carlsen of Denmark 6-3 6-4.
Agassi, winner of the Australian Open last month, withstood a tremendous effort by Voltchkov who kept the American on his heels with his huge forehand and bullet first serves.
Down 5-6 in the second set tiebreak and facing a match point, Agassi took a high ball out of the air and knocked off a crisp forehand volley winner.
The 32-year-old then punched a backhand volley winner before cracking a backhand down the line and yelling to the crowd.
"I've made a living of that shot," Agassi said afterwards.
"At that point, it was do or die and I was either going to miss it or he wasn't going to get to it."
The 24-year-old Voltchkov played a brilliant first set, matching Agassi from the baseline and winning the tiebreak when he pummelled a forehand drive volley winner, boomed one of his 20 aces and watched Agassi double fault to take the tiebreak 7-3.
"I was well aware of how well he was playing," said Agassi. "There's not a whole lot you can do when he's playing well except stay in the match and make him earn it to the end."
Agassi wouldn't go down quietly and stayed strong in the second set, frequently pulling his opponent off the court in crosscourt rallies. In the third set, the eight-times grand slam title winner dominated his tired foe, who quickly deflated.
"It was his endurance," said Voltchkov, who smacked 49 winners but committed 56 unforced errors.
"He plays so fast and so hard that once I got to the third set his fitness was better. I couldn't take that extra step. I gave it everything I had, but he never slows down."
Agassi, who hasn't lost a match since the year-end 2002 Masters Cup in Shanghai, was impressed by the Belarussian.
"His forehand was one of the toughest I've ever faced," he said.
"If he can play like that consistently, he'll be ranked a lot higher." Agassi and Blake have played twice, with Agassi winning their first meeting in 2001 and Blake upsetting his countryman in the semi-finals of Washington last year, when he won his first title.
"It should be fun," Agassi said. "James is a great competitor and athlete. He's a class act."
Blake said: "I have got a lot of work cut out for me, but I have nothing to lose."
In reaching his first semi-final since 2000, 26-year-old Gimelstob won a tense battle of serve-volleyers. Gimelstob, who has been practising with Pete Sampras and Andre Agassi, said he is a different player these days.
"The key for me is how much work I've put into my serve and my attitude," he told reporters. "I'm much more relaxed out there. I'm still an intense person but I control my emotions a lot better." The 6ft 5ins Gimelstob was not too calm around the net, though, diving on the hard court twice in the second set and grazing his elbow.
"I'm right up there with Boris Becker," said Gimelstob. "I was determined not to let those balls go by."