Timing in tennis is a very sneaky business. It's a euphemism the pros like to use to make you concentrate on the single instant of striking the ball, but it really covers other aspects of the game as well: footwork, preparation, concentration and follow-through.

The beauty of the trick is that it works. Get your timing down and the rest of the your game will have followed already. This is why Arthur Ashe calls it playing "in the zone" (as in Twilight Zone)-playing with such fluid coordination that you hardly know where you are. It's also what zen tennis guru Timothy Gallways calls the state of Self Two.

There are plenty of ways to recognize that your timing is off. Chief among them is hitting balls over the fences. Another is that you're meeting the ball after it's gone past you. Another is that every shot from the other side of the net looks more like a Nolan Ryan fastball than a tennis shot. Welcome to spring.

Probably the best way to retrieve lost timing is to put rhythm back into your game. Try to avoid jerky starts and stops in favor of a constantly moving flow. Even when waiting for your partner to return a shot down the middle, keep your feet moving in a bouncing rhythm all the time. When you begin to move to the next shot, it will flow naturally out of this continuous movement.

If possible, begin the season on a relatively slow court, such as clay, and try to choose a partner with steady rhythm. It's best not to play a match, but rather to "hit" balls for an entire hour. But if your competitive urges are irrepressible, try to warm up for at least half an hour.

Concentrate on steadiness: Think of yourself as Chris Evert (who is off on her honeymoon anyway), defending the baseline at all costs. Forget about skimmers and winners; make every ball clear the net by four or five feet and land in the backcourt.

In the matter of execution, focus all your concentration on one thing: hitting the ball well in front of you. Where your mind and eyes go, your feet and racked will follow. Enjoy.

Q-How long will it take to get my timing back?

A-Three one-hour sessions in one week should do it. Reptition is the key. Hit a lot of balls. Relax and try to feel comfortable on the court. Practice patience.

Q-I thought tennis timing was like riding a bicycle or driving a car: once you've got it, you never lose it.

A-Playing tennis is more like ballet than bicycles; it requires constant practice to achieve and maintain a perfectly coordinated series of motor reflexes. Even Baryshnikov goes to ballet class.

Q-I seem to have more problems with timing on my forehand than my backhand. Why is this?

A-This is no surprise. The backhand involves wrapping your racket arm around your body, then opening it up. This is a more natural athletic movement than the forehand, which involves opening up your chest, then swinging across it without moving your shoulders too soon. Try hitting forehands off a backboard for 15 minutes before you play.

Q-Are timing and rhythm the samething?

A-At the highest levels, they are not. Jimmy Connors has superb timing but an unrhymthic style of play, while Bjorn Borg has excellent timing and a more fluid game. A top pro can have good timing without good rhythm, but nobody can have good rhythm without good timing. For the amateur player, it pays to work on them simultaneously; one tends to flow from the other. CAPTION: Picture, no caption, By Richard Darcey