John Isner beats Ryan Harrison in opening round at Newport

Newport: Two-time defending champ John Isner defeated fellow American Ryan Harrison 7-6 (0), 6-2 on Monday in the opening round of the Hall of Fame Tennis Championships.

The 6-foot-9 (2.05-meter) Isner rode his big serve to win his 11th straight match on Newport's grass courts.

The 28-year old Isner showed no effects from a left knee injury that forced him to retire from his second-round match at Wimbledon. He blanked Harrison in the first-set tiebreaker and then broke him twice in the second set before Harrison hit a backhand return long on match point.

On his way to the title last year, Isner held serve in 57 of the 58 games he played. It was a similar formula on Monday.

"Just getting the first one out of the way is critical for me," he said. "I was happy how I played in the second set, took care of my serve well. I felt like I was in a lot of his service games, especially in that second set."

Top seed Sam Querrey is slated to face fellow American Tim Smyczek is his first-round match on Tuesday.

Also Monday, Poland's Michal Przysiezny beat 15-year-old American Stefan Kozlov, who was making his ATP debut, 6-3, 6-7 (9), 6-4 in a match that lasted nearly 2 ½ hours.

Kozlov broke to go up 4-3 in the third set before calling for the trainer, who worked on his right hip.

"I slipped in the first set on my hip and it kind of got progressively worse," Kozlov said.

The match ended with the youngster limping before falling to the ground as he made his way to the net. He sat in his chair for a while with a towel over his head before slowly walking off the court.

"I was hanging in there and started cramping," he said. "It's kind of tough to play when you're cramping. Now I know I could actually win. I couldn't believe I could win a set."

The tournament is held in conjunction with induction ceremonies into the International Tennis Hall of Fame. Martina Hingis leads the 2013 class that will be enshrined on Saturday before the semifinals.

In other first-round matches, France's Adrian Mannarino, who advanced at Wimbledon when Isner retired and reached the fourth round, beat American veteran James Blake 6-4, 5-7, 6-1 and Japan's Yuichi Sugita got by Canadian Jesse Levine 7-5, 7-5.