John Isner overwhelmed Gilles Muller of Luxembourg in the third set to win 7-5, 6-7 (3), 6-1 on Saturday and reach the Atlanta Tennis Championships final for the second straight year.
Isner, the No. 3 seed, will face fellow-American and top seed Mardy Fish in Sunday's final. Fish beat Ryan Harrison 6-2, 6-4.
Fish, No. 9 in the world, beat Isner in the 2010 Atlanta final and has not lost a set this week. Isner can improve his No. 35 ranking by beating Fish.
Coming off a victory in the Hall of Fame Tennis Championships on the grass courts in Newport, Rhode Island two weeks ago, Isner said his game is soaring with his confidence on Atlanta's hard courts.
"I've been waiting for this feeling for about four or five months," Isner said. "Now that I've got it, I don't want to let it go."
Isner's attempt for back-to-back wins resembles Fish's climb last year. Fish had never won two straight tournaments before winning in Newport and Atlanta.
"I came in on a roll," Fish said. "I had never won two tournaments in a row last year. I felt like I was a different player than in years past and had yet to prove it. That was sort of the start of my run to the top 10."
The 6-foot-9 (2.06-meter) Isner, who is best known for his powerful serves, said he is making good decisions that help him enjoy a more complete game.
"It's as simple as confidence," he said. "I always play my best when I'm confident. I move my best when I'm confident.
"I'm not the fastest guy out there but I feel I've been moving well this week and that comes with having a clear mind and making the right decisions on the court."
In the key game of the match, hit an overhand winner to break Muller's serve for a 2-0 lead in the third set. Muller reacted by slamming his racket to the court, demolishing the racket.
Muller never recovered. Isner broke the left-hander's serve again for a 4-0 lead.
"I thought I made a lot of hard work in the second set to win that set and then right away in the beginning of the third one, I threw all my chances away," Muller said. "It was hard to take."
It was the second straight year Isner beat Muller in three sets at Atlanta.
Harrison, 19, was the first American teen to play in an ATP World Cup semifinal since Sam Querrey lost to Russia's Dmitry Tursunov in July, 2007 in Indianapolis.