He’s tall, lanky and the tennis racket in his hand looks oddly minuscule by comparison.

The goofy grin that almost never leaves his face is reminiscent of a fraternity boy downtown on a Saturday night, not a professional tennis player who has established himself as one of the best Americans in the sport.

And though he is 6-foot-9 and appears he should be dunking basketballs rather than stepping on a tennis court, John Isner is making waves on the national scene.

JOHN ISNER

Ranked No. 17, Isner teamed up with his fellow Americans on Thursday for the first round of the Davis Cup, against Switzerland.

In that first match he faced a living legend, the third-ranked player in the world and one of the greatest of all time — Roger Federer.

And somehow, he came up with the victory, 4-6, 6-3, 7-6 (4), 6-2.

Four glorious sets of big serves and even bigger forehands led the former-Bulldog to the unlikely victory, a win the 26-year-old called the biggest of his career.

This is the same Isner who participated in the longest match in tennis history, a 2010 Wimbledon first rounder against Nicolas Mahut that lasted 11 hours and five minutes spread out over three days.

Isner also won that bloodbath, in a tiebreaker of the fifth set, 70-68.

But despite all of that success, perhaps the most intriguing part of his career has been the journey he took to get there.

Tennis fans in the United States know that all too often the best talents never seriously consider playing tennis at the collegiate level, favoring the high-stakes of international tournaments that promise the dream of luxury and fame.

But Isner chose to play collegiate tennis and was highly successful in doing so, leading the Bulldogs from 2004 to 2007 and winning a national championship.

Not only that, but the Bulldog was able to find success after his college career — something that young tennis players could do well to notice.

Given four extra years to develop his game before adding the pressure of heavy expectations, Isner allowed himself to mature before stepping into the role of a professional.

And even if he looks odd while he’s doing it, there’s no arguing with the results — the kid’s a champ.