ATLANTA -- Top-seeded John Isner figured he would struggle in his first match Thursday in the Atlanta Open. He had no idea he would barely beat 19-year-old wild-card entry Christian Harrison 7-6 (9), 4-6, 7-5 to avoid an upset and reach the quarterfinals.
Isner is ranked No. 22 in the world. Harrison is No. 373, and was playing his second ATP main draw match.
So even though Isner is accustomed to scuffling when he has had a bye and then plays an opponent who has already warmed up with a win, he didn't foresee needing three sets.
Harrison fought off three match points, and only when Isner boomed his 28th and 29th aces back-to-back -- one game after breaking Harrison for the first and only time -- did Isner win.
"A guy like Christian doesn't have much to lose. A lot of times a person like that can come out and play horrible, or be pretty good. He was very good," Isner said. "I was very fortunate just to win. ... He's up and coming. We use that term a lot, but he really is.
"You never want to win 7-5 in the third, 2½ hours in humid conditions like this, but I'll take it."
Harrison and his 21-year-old brother, Ryan, are no secret. Christian was one of the world's top junior players, and the pair reached the doubles quarterfinals of the U.S. Open last year. Ryan earned his first ATP win at age 15 in 2008.
Their father, Pat, was a pro briefly years ago, and has been their coach for years. The family also moved from Austin, Texas, to Bradenton, Fla., to work with coaches at the Nick Bollitieri Academy.
As with most Bollitieri students, Harrison patrolled the baseline chiefly in a defensive mode. "Credit him. He made a lot of balls and that's what he does," Isner said. "It was frustrating out there."
Each player broke serve once, and both were critical.
Isner double-faulted to give Harrison the second set point, but the teenager would return the favor.
At 5-5 in the third, Harrison was serving at 30-0 and very much in contention to join Ryan in the quarterfinals hours after his older brother upset fourth-seeded Igor Sijsling 6-4, 6-3 after trailing 1-4 in the first set.
Then, Christian double-faulted. Eventually, he sent a forehand return into the net as Isner broke to 6-5 and then served for the win.
"It was exciting, probably the biggest crowd that I've played in front of," Christian said. "The whole time I felt like I was under control. I got a little hesitant on the break point at 5-all, kind of rolled a forehand, but . . . (Isner) came through clutch there in the end.
"It certainly hurts at 5-5, I double-faulted. Whenever it's that close, you don't want to give away points."
Friday, Isner will play Jeff Blake, a 6-3, 6-2 winner over eighth-seeded Evgeny Donskoy 6-3, 6-2.
In the other quarterfinals, Ryan Harrison will play Santiago Giraldo; second-seeded Kevin Anderson will meet Denis Istomin; and seventh-seeded Lleyton Hewitt, who won his second-round match Wednesday, will play third-seeded Ivan Dodig.