A correct serving motion resembles a firm overhand throw. Check your motion by actually throwing a few tennis balls over the net into the service box. Are they similar?

Some players "push" the serve over and in. It’s not just the inexperienced novice either. It’s often the intermediate or advanced player who has tightened-up under pressure.

You can easily spot a "push" serve; it’s practically the opposite of a natural throw. But how do you know when it’s actually happening while you’re competing?

*Your motion gets shorter and smaller

*Your toss gets lower and lower

*Your follow-through disappears

*You avoid using your shoulders face the net head-on, and "arm" the ball

When the match is over and the pressure is off, go to a practice court to rehearse your serve. Take an old sock with you (the longer, the better). Put a ball in the toe end of the sock an grab the sock by the cuff end. Go through some throwing motions, hanging on to the sock. Now lift an imaginary ball with your tossing hand to replicate the timing of the toss.

If you’re actually "throwing", the ball will speed past your hand at the top of your swing. If you’re "pushing", the ball will lag limply behind your hand.

Gary Sherby is tennis director at Racquets and Togs Tennis Center, 115 Bradford St., just off the downtown square. His tennis tips appear Sundays.