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The Loop

Martin Kaymer is on the range hitting golf balls wearing a tennis ball necklace

Martin Kaymer made nine birdies and nine pars en route to a course-record tying 63 on Thursday at the Players. How did Kaymer do that? By hitting almost 90 percent of the greens in regulation (the field average was about 65 percent). How did he do that? With a tennis ball, it seems.

Since retooling his game after becoming World No. 1, Kaymer has worked on making his game more controlled. He's switched his ball flight from a draw to a fade and tried to ensure all parts of his swing are working in sync. One way he's doing that is by practicing hitting golf balls with a tennis ball -- which he fashioned into a necklace -- placed between his wrists. Golf Channel filmed him doing the drill on the range Friday morning: