ESPN Tennis

HOUSTON -- James Blake overcame some early struggles to beat fellow American Alex Kuznetsov 7-6 (4), 6-1 on Thursday in the second round of the U.S. Clay Court Tennis Championships.

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The second-seeded Blake was down a break in the first set before rallying to take the tiebreaker on a backhand approach shot up the line.

The world's ninth-ranked player was unable to capitalize on four break points in the second game of the final set, but he broke Kuznetsov in the fourth and sixth game to advance to the quarterfinals.

In the first set, Blake broke Kuznetsov in the 11th game, but the younger American took Blake's serve in the next game to send it to the tiebreaker.

Windy conditions prevailed late Thursday, and Blake said his footwork suffered from it in the first set.

"For me, if I'm not moving my feet I feel like I don't get anything on the ball, because I'm kind of reaching for it and just arming as opposed to getting behind it and really ripping it," he said. "You kind of scratch out those kinds of sets, and I did, and played pretty well at important times in the tiebreaker and just managed to eek my way out."

Third-seeded Tommy Haas of Germany beat Frenchman Nicolas Devilder 6-3, 6-4 later Thursday night. Haas will play Ivo Karlovic of Croatia, who won by default. Karlovic has beaten Haas twice on clay, in Rome in 2004 and last year in Munich.

Blake, who sometimes practices with Kuznetsov in Florida, told the crowd after the match to keep an eye on the 20-year-old Ukrainian-born American.

"He's way ahead of schedule," Blake said. "I like his future."

Blake will play Juan Monaco of Argentina on Friday night.

Earlier Thursday, Monaco wasn't bothered by the blustery conditions, beating Amer Delic 6-2, 6-3 in a second-round match.

The eighth-seeded South American needed just 66 minutes to gain a quarterfinal berth, breaking Delic in the first game of each set as wind swirled around the stadium court.

"Once you get into the court you have to play with all the things, windy or no windy," said Monaco, who got his first tour win earlier this year in Argentina.

Diego Hartfield, Monaco's countryman, warmed up for his match against the 6-foot-10 Karlovic but had to default before play began due to a stiff neck.

"I feel sorry for him, but I'm also pretty happy that I'm in the quarterfinals," Karlovic said.

Last year's runner-up, Jurgen Melzer of Austria, will face qualifier Mariano Zabaleta of Argentina in another quarterfinal Friday. Zabaleta, who lost to Melzer in their only meeting in Vienna in 2002, knocked out defending champion Mardy Fish of the U.S. in three sets Wednesday.

In the other quarterfinal Friday, Albert Montanes of Spain plays American Vincent Spadea.

Copyright 2007 by The Associated Press