Great servers have realized that power and pace are not the end-all and be-all, and that their killer shots must be backed up with a solid return game.

According to NASA, it's not just superstition—there are actual aerodynamic properties at play when it comes to the fuzz that forms on tennis balls.

[The Q] decided to solve this problem with a unique design: tires that use tennis balls as the cushioning medium instead. The build begins with small cut sections of plastic water pipe. These are ...

But, of course, serving the ball inbounds is just the first step ... per hour faster than the average female professional tennis player. Now, part of that speed is the result of pure strength.