Unhinging the wrists through impact creates that last-second burst of speed you see in better players. Amateurs tend to let the wrists unhinge too early, but the root of the problem is in the lower body. If you fail to make a good lateral move toward the target on the downswing, your left leg straightens too soon, which causes you to throw the club away from your body and unhinge your wrists way before impact (above, left).
Here's a drill I use with my students who need a better lateral shift. Stick a shaft or similar object in the ground just outside your left foot and practice hitting drivers trying to bump the shaft with your left knee as you start down (above, right). You might not actually contact the shaft, but you'll shift to your front side, and your arms and the club will drop into a powerful inside position, with the wrists staying fully hinged.
So feel as if you're squatting into your left leg as you move laterally to your front side. You'll have a much better chance of maintaining that powerful wrist hinge as you swing into the ball.
JIM MCLEAN is ranked No. 4 on Golf Digest's list of America's 50 Greatest Teachers. His golf academy is headquartered at Doral Golf Resort & Spa in Miami.