The American took out compatriot Ryan Harrison in the final with the help of 23 aces. (AP)

It is no secret that John Isner’s serve is one of the biggest weapons in all of tennis. When the now top-ranked American man has success on the court, it is usually led by one of the biggest point-starter’s the sport has ever seen.

Isner’s serve—with which he held 75 times from his win in Newport through the first set of last week’s final in Atlanta—helped him capture his fourth Atlanta title with a 7-6 (6), 7-6 (7) victory over compatriot Ryan Harrison.

Before analyzing how Isner uses his best shot so well, let’s just take a look at the literal damage that it did to his opponent in the Atlanta final.

Again, the value of Isner’s serve is no secret. But the question is, what makes it so effective? Isner’s 6-foot-10 inch frame gives him a unique advantage that causes a multi-pronged effect. The University of Georgia alumnus has the ability to find more angles on the court than nearly anybody on tour because of the height at which his racquet makes contact with the ball.

Plus, he uses a nearly perfect leading ball toss slightly inside the court, allowing him to push off the surface with his excellent knee bend, which he uses to explode up to his toss.

When many fans think of a big serve, they think speed. But you can argue that Isner’s most effective serve is actually one that is based on placement: his slider out wide in the deuce court. Take a look at this delivery against Harrison:

Nobody in the world could put that ball back into play. When Isner shifts his body weight, allowing him to explode as far into the court as he does to strike his serve, he accesses incredible angles. 

A slice serve is typically cut off by stepping diagonally to the ball, which stops the ball from spinning too far away from the court. But Isner is able to land his slice shorter in the service box—without reducing his velocity all that much—making it impossible to return unless you're camping out in the doubles alley. Isner’s height also causes his slice to bounce higher than most kick serves.

Much like his slice in the deuce court, Isner can hit a nasty kick serve in the ad court, which bounces over most players’ heads and takes them out into the doubles alley.

Now there is another dilemma. If you protect the wide delivery against Isner on either side, you give up the middle of the court, which is naturally a higher percentage serve to hit since the net is lower—36 inches tall compared to 42 inches at its highest out wide. Camp out wide for one serve, and Isner can hit another one at 140 m.p.h. down the T.

Harrison certainly recognized what he was forced to deal with on Sunday. When he broke immediately to start the second set, that was an accomplishment in and of itself.

So while Isner has hit more than 9,000 aces in his career, he does not simply blast it by his opponents — although he could do that too. The American has many service options to frustrate opponents with, just ask Ryan Harrison’s bruises.

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