WASHINGTON (TICKER) -- It was tight, but Andy Roddick knew the way to the final at the Legg Mason Tennis Classic.
The top seed, Roddick pulled out the key points to post a 7-6 (9-7), 7-6 (7-5) victory over No. 7 Ivo Karlovic of Croatia in the semifinals of the $600,000 hardcourt tournament on Saturday.
With the win, the 24-year-old American advanced to the final for the third time in his last five appearances here. Roddick captured titles in those two previous finals, winning in 2001 and 2005.
Roddick, who missed this tournament last year with a side injury, will take on surprising American John Isner, who rallied to outlast ninth-seeded Gael Monfils of France, 6-7 (4-7), 7-6 (7-1), 7-6 (7-2), in Saturday's other semifinal.
With both Roddick and Karlovic in the possession of two of the game's top serves, breaks were nearly non-existent.
The American did take advantage of his only break chance of the match in the first set, but still found himself trailing 4-1 in the tiebreaker. He stormed back to record eight of the next 11 points.
Roddick did get some help, as Karlovic put a volley into the tape to even the score at 4-4. The American eventually got it to 6-5, but dumped a return of serve into the net. At 8-7, Karlovic hit a forehand long to end the set.
In the second set, both players held serve and were knotted at 5-5 in the tiebreaker before Roddick ripped a backhanded passing shot down the line. The match ended on the next point when Karlovic put a backhand into the net.
Despite only graduating from the University of Georgia in the spring, Isner has not taken long to break through on the ATP Tour.
Playing in just his second tournament as a wild card, Isner followed up his shocking win over second-seeded Tommy Haas with another three-set marathon.
The 22-year-old North Carolina native had suffered a first-round exit at Newport in his only other ATP tournament this year and is ranked No. 416 in the world.
But he has enjoyed a spectacular run here, knocking out Great Britain's Tim Henman, No. 8 Benjamin Becker and Haas before rallying to eliminate Monfils.
A member of Georgia's national championship team in the spring, Isner used a powerful serve to oust Monfils, blasting 23 aces to give him 53 in his last two matches.
Monfils had 25 aces of his own and served for the match after breaking Isner at 5-5 in the third set, but Isner broke right back and dominated the tiebreaker.
In his five matches, Isner has ripped off 134 aces, the most in the field.
First prize is $74,250.