The crocodile on his shirt was swimming in sweat and John Isner looked like a man treading water on the blue court in Atlanta.

Facing triple break point against nemesis Lleyton Hewitt in the seventh game of the final set, Isner unloaded three massive serves to hold and denied another break point in his next service game, eventually finding his comfort zone in the tie breaker.

The top-seeded Isner smacked 21 aces to squeeze out a 6-4, 4-6, 7-6 (5) victory and reach his third Atlanta final after a two hour, 23-minute test.

Serving in the ninth game, Isner dug out of a 15-30 hole with a pair of 130 MPH aces out wide —his ninth and 10th aces of the set —followed by a forcing forehand to hold for 5-4.

Isner imposed his forehand in the following game, hammering a deep forehand that skidded off the baseline followed by a short-angle inside-out forehand winner for set point. Another inside-out forehand drew an error from a lunging Hewitt, whose squealing sneakers amplified his effort while he stretched for the ball,  as Isner trotted to his seat with a clenched first and one-set lead.

Former U.S. Open champion Hewitt still looks at home on hard courts, but he hasn't reached a hard-court final since winning the 2007 Las Vegas title and competed with the driven demeanor of a man willing to do whatever was required to reach the finish line. Hewitt rallied from a set down to beat Isner at Indian Wells in March, repeated the feat two weeks ago in the Newport semifinals, snapping Isner's 13-match winning streak on the Newport grass in the process, and put more returns in play as the match progressed.

The feisty Aussie stands 5-foot-11, nearly a foot shorter than the towering American, but Hewitt used his anticipation and expansive reach to poke back returns that Isner usually sees bounding off the back wall. Stabbing a return back, Hewitt earned break point when Isner pushed a forehand volley to the net and broke for 4-3 when Isner, who tends to take one loping stride rather than short preparation steps on his volley, nudged another forehand volley into net.  A lethargic-looking Isner netted a slice backhand for set point and Hewitt hammered an ace down the middle to seal the set.

Isner took a near seven-minute break after the second set, returning to run off five consecutive points to open the finale. The 32-year-old Hewitt, contesting his third semifinal in his last four tournaments, hit a high backhand volley to earn triple break point at 3-all, but Isner's serves screamed defiance. He blasted a 137 MPH serve wide to save the first. On the second, Hewitt's blocked return teetered on top of the net — momentarily — before plopping back on his side of the court. Hewitt got a look at a second serve on the third break point, but Isner hit a wicked kicker wide to erase it. Another hellacious kick serve out wide helped him hold for 4-3.

Former No. 1 Hewitt doesn't hit nearly as hard, but his slice serve has plenty of sidespin and stays low and he tormented the big man, hitting 12 aces and winning 76 percent of his first-serve points. Isner is the ATP's most imposing tiebreak player and built a 4-1 lead only to see Hewitt battle back to level at 5-all. Attacking behind a forehand down the line, Isner stuck a slick angled backhand volley winner for match point then whipped a second serve that rattled Hewitt's racquet to end it.

Isner, who raised his ATP-best tie breaker record to 24-6 on the season, will face either second-seeded Kevin Anderson or 21-year-old American Ryan Harrison in Sunday's 3 p.m. final televised nationally by ESPN2.