Here I was, a 48-year-old club player, staring up at the Isner service motion that once produced a 149-mph serve at the Western & Southern Open. Isner's racket ripped through the ball.

John Isner looks down at me from across the net. The best tennis player in America is about to unleash the best serve on the planet and let me – a 49-year-old club player – attempt to return it.

The 6’10” Isner’s technique is unsurpassed when it comes to what instructors call the “pinpoint” motion. This is when the server’s back foot moves forward prior to launching the delivery.

Isner represented something different. He showed what it would look like for a player to come on tour and win lots and lots of matches with one huge weapon: A serve that produced an all-time ...