This year marks the 50th anniversary of TENNIS Magazine's founding in 1965. To commemorate the occasion, we'll look back each Thursday at one of the 50 moments that have defined the last half-century in our sport.

Since at least the 1920s, speed has been one of tennis’ major attractions. In that decade, Bill Tilden developed his “cannonball” serve, and legend has it that in 1931 he was clocked hitting it 163.3 M.P.H. More important, though, was how effective Tilden was with it; his power elevated him above all other players of that era, something that his countrymen and countrywomen have taken to heart ever since. Pancho Gonzalez, Stan Smith, Roscoe Tanner, Pete Sampras, Andy Roddick and Venus and Serena Williams have all blown away opponents and fans with triple-digit pace. In the 21st century, players don’t even need a serve to generate that kind of speed; Juan Martin del Potro has hit his forehand over 120 M.P.H.

Rising speeds have effected the game in all kinds of ways. With the advent of oversize racquets and new materials in the 1980s, officials realized that human eyes could no longer keep up with the ball. So they enlisted their own technology, first in the form of Cyclops’ infrared beams, and later by the computerized Hawk-Eye system, to help them call the lines on serves. In 1989, at the International Players Championships in Miami, the sport debuted a device that didn’t call the serves, but timed them—a radar gun. Serve speeds like Tilden’s had been measured in the past, but with technology that was either unreliable (ballistic chronometer) or took too long to read (high-speed photography). The radar gun offered faster, more precise readings, and, just as important, a new statistic that the tours could use to promote their players.

Mark Philippoussis, Greg Rusedski, Andy Roddick, Brenda Schultz McCarthy, and Venus Williams, among others, soon became almost as famous for their record-breaking service speeds as they were for their victories and rankings. In 2007, the WTA started a Power Index, which used information gathered from Hawk-Eye to rank players based on the average pace of six of their shots. “It’s another way to recognize athleticism and sheer power of our top players,” tour president Stacey Allaster said at the time.

On the surface, power tennis seems to have abated a little in the years since, especially on the men’s tour, where defense and running are now the name of the game. Spin, created by new string technology at the turn of the century, has been the game’s latest advance. The fastest serve speed, after steadily ascending from the 140s to the 150s and into the 160s, has stalled. Ivo Karlovic’s 156-M.P.H. serve, however, which he hit in a Davis Cup tie in 2011, has topped the ATP’s official list for five years now (Sam Groth’s 163.7 mph blast from the following year was hit at a Challenger event, which the tour doesn’t recognize in its official records). Still, as the gasps from the crowd whenever a bomb serve is hit attest, speed still kills in tennis.