WATCH: Knowles teaches NBA's Dwight Powell how to serve

NBA and ATP stars recently shared the tennis court during the fourth annual Dirk Nowitzki Pro Celebrity Tennis Classic in Dallas. For the most part, the hoopers were impressive. The raw athleticism was there in spades, the technique, however, not so much.

Case in point, Dallas Maverick’s power forward Dwight Powell’s serve. “Just tap it in” may work on the putting green, but not on a tennis court.

At 6’11” 240 pounds, the former Stanford Cardinal standout is a force to be reckoned with. When Powell cocks back for a slam dunk, even the biggest, baddest NBA players get out of the way.

Back on the court, after facing Mark Knowles in a 10-point-tiebreaker, Powell got a quick lesson from the former doubles No. 1. Knowles couldn’t stand idly by and watch a nearly seven-feet-tall athlete with a 35” vertical jump just patty-cake his serve in. Immediate action was required.

The theme of Knowles' lesson was simple: Reach up and hit the ball at its highest point. When you are that tall, simply snapping the wrist on contact will yield a formidable serve. After a few attempts, Powell began to catch on. The results speak for themselves.

Powell and his newly improved serve will be back next year, and the competition better watch out.