WINSTON-SALEM, N.C. (AP) -- John Isner admits that he usually has a rough time in his first tournament match.
After the way he bounced back in his opener at the Winston-Salem Open, Isner hopes that can give him the confidence to win another title.
Isner, the tournament's top seed and two-time winner, overcame a rough start against fellow American Bradley Klahn to take a 7-6 (7-5), 6-2 victory Tuesday in the final tuneup before next week's U.S. Open.
Isner served 13 aces - one clocked at 138 mph, and several others at 130-plus - and broke Klahn's serve twice in the second set to improve to 11-0 all-time at the Wake Forest Tennis Center, where he won the title in 2011 and 2012.
''The first set was pretty shaky, really,'' said Isner, who was born in nearby Greensboro. ''But a lot of times, the first matches for me are a little tough. Tonight, it was a little tough, but I'm hoping I can get better and smarter.''
Isner will next face 13th-seeded Mikhail Kukushkin of Kazakhstan, who Isner beat in four sets in the second round at the French Open last May. He'll need to get off to a better start than he had against Klahn.
The 6-foot-10 Isner had 10 aces and five service winners in the first set against the 115th-ranked Klahn, but also committed 30 forced and unforced errors in the set. That allowed Klahn to stick close and force a tiebreaker, but Isner got the advantage with a pair of mini-breaks off Klahn's serve.
''I actually thought I did a very good job making him earn a lot of his service games, especially in that first set,'' Klahn said. ''But on those break points, there was nothing I could do. He played two good points on my serve, then he hit three big serves. That's the way it is with John, and I knew that going in.''
That swung the match's momentum Isner's way, taking two straight service breaks to build a 4-0 lead in the second set as Klahn had trouble finding the range on his ground strokes.
''(Klahn) played pretty well in the first set,'' Isner said. ''But his level dropped off quite a bit early in the second set. I was able to take advantage of that.''
While Isner advanced, three of the top six seeds were eliminated in the second round. Third-seeded Tommy Robredo of Spain lost to France's Nicolas Mahut 6-1, 7-6 (7-0); fourth-seeded Leonardo Mayer of Argentina was upset by Belgian qualifier David Goffin 6-3, 6-1; while Poland's Jerzy Janowicz stunned No. 6 seed Joao Sousa of Portugal 6-1, 3-6, 7-6 (7-5).
However, No. 2 seed Kevin Anderson of South Africa overcame a shaky second set to beat France's Adrian Mannarino 6-3, 2-6, 6-4.
The 6-foot-8 Anderson, ranked 20th in the world, served 16 aces and almost as many service winners. Mannarino used his ground game to force Anderson into 24 errors in the second set, breaking his serve twice en route to taking the set and evening the match at 1-all. But Anderson got a key service break in the seventh game of the third set, and closed out the match with two aces and a service winner in the deciding game.
In other matches, Sam Querry beat fellow American Steve Johnson 6-4, 6-3; Edouard Roger-Vasselin of France defeated Kazakhstan's Aleksandr Nedovyesov 7-6 (11-9), 6-7 (5-7), 6-4; Donald Young of the United States beat Canada's Frank Dancevic 6-1, 6-3; Italy's Andreas Seppi downed Argentina's Federico Delbonis 7-5, 6-7 (4-7), 6-2; Spain's Marcel Granollers beat Paul-Henri Mathieu of France 6-3, 6-3; Kazakhstan's Mikhail Kukushkin defeated Robin Haase of the Netherlands 5-7, 7-6 (7-2), 6-4; Taiwan's Yen-Hsun Lu downed Blaz Rola of Slovokia 6-4, 7-5; and Spain's Pablo Andujar beat Igor Sijsling of the Netherlands 6-4, 6-3.
Lukas Rosol of the Czech Republic also advanced after American Ryan Harrison withdrew in the second set. Harrison had won the first set 6-3, but was trailing 2-1 in the second when he suffered a strained muscle in his right shoulder.