The 90% Zone

Unforced errors are arguably your worst enemy when trying to play winning tennis. Putting the ball in the net doesn't even give the other guy a chance to make his own mistake. Making an error saps your confidence and removes pressure from your opponent. Why give him a mental advantage? Imagine if you made no errors, and your opponent had to hit a winner for each point he won. That would be impressive even if you lost. Well, it's within your control if you understand what you can and can't do consistently and have the discipline to make the right shot selections.

Nobody's perfect, and trying to make absolutely no errors might lead too far down the path of timidity. So, what if you targetted being 90% error free. We'll call that being in "The 90% Zone." That means for every ten shots you try, only one is not in play (in the net, long, wide, etc.) Arthur Ashe used to say that you should expect to hit at least six balls to win the point. So, what happens if two players are in the 90% zone. If neither hits a winner, that means that after one shot there is a 90% chance the ball will be in play, after two shots 81%, after three 73%, four 66%, five 59%, six 53%, seven 48%, etc. This shows that Ashe's rule of thumb is generally in line with the 90% zone. In fact, if one player expects to hit six shots, then that would mean a 12 shot rally which only has a likliehood of 28%. So, it's arguable that at the professional level, the percentage should be even higher - like maybe 95%. But, let's start with a reasonable goal at 90%. After all, wouldn't we feel like we're playing good tennis if half of our points lasted at least seven shots.

Achieving 90% Zen

So, how do we achieve the 90% zone? The first step is to expect it. You should be disappointed when you miss a shot and thinking about why you missed it. For every missed shot, you should review your footwork and your stroke. You should also consider the type of ball your opponent gave you; For example if you tried to rip a backhand passing shot cross court off of a deep approach shot and missed horribly, that should tell you to try a different shot next time. Deep approach shots put you on the defensive and you should be thinking lob. On the other hand, maybe your opponent gave you a sitter in the middle of the court, and you went for a winner but put it in the net. Commonly, this is caused by not moving your feet enough to get in the right position. So, concentrate on getting to the right spot AND give yourself more margin next time.

It's also important to know what shots you can make 90% of the time. You should know this going into your match and adjust based on how you are playing during the match. A lot will depend on the type of ball your opponent is giving you, so you have to be tracking how well each of your shots is working that day and make adjustments. For instance, if you know you are about 30% on down-the-line, flat backhands, you shouldn't even try it in the match - not even once. If you want to try to hit that in a match, spend some time during practice learning to hit it. Otherwise, use another option like a slice backhand down the line.

Here's Bollettieri's Thoughts on Knowing Your Game:
Becoming Aware of Yourself

Making Adjustments

Here's a table of adjustments to make to your shot selections based upon a typical 4.0 to 4.5 player.

Shot	1st change	2nd change	3rd change	4th change
forehand	more topspin	more arc	more margin	more relaxed
backhand	slice	lob	more margin	more relaxed
approach	slice	down the line	more margin	more relaxed
volleys	let ball come to racquet	small tap	angle off high balls
overheads	stay aggressive with power and placement		use straight arm if stretched or moving forward

more topspin: hit the ball with more topspin
more arc: aim for a higher spot over the net (e.g. 3 feet)
more margin: aim for a spot further inside the lines
more relaxed: take some pace off by relaxing your entire stroke
slice: hit a slice shot instead of coming over it
lob: hit a lob that is either very high or will land deep
small tap: just barely tap the volley, using placement instead of power

You should make adjustments quickly. So, for instance, if you miss a shot badly the first time, immediately make the first change. If you miss a shot twice in a row, definitely make the first change. Stick with your adjustments until you've hit nine in a row successfully. Then consider whether you want to change back. For instance, if you have switched to your slice backhand, and you're having success, stick with it. However, if you're opponent is teeing off on the nine shots you've hit, you need to change it up in some way such as: switching back to a topspin backhand, going for more depth, switching to a lob, aiming for a different target, etc. But don't panic; if you're putting 90% of your shots in play, congratulations - you're playing real tennis!

Going For More

Once you've established consistent play in your match, there may be times when you want to go the other direction and see if you can get a rythym for your more aggressive shots. The key is to look for strategic opportunities. One of the best times to play a more aggressive point is when you are down 0-40. If you are down 0-40, you've really got nothing to lose. If you're serving, go for a big serve (maybe an ace). If you're returning, take a good cut at the ball with the aim of putting your opponent off balance. The key is to practice hitting the shot in the match. You may find that those shots go in. That doesn't mean that you should try for that much every time, but now you know whether you should try those shots on a big point like say 30-30 or break point. Another good time is when you are up 40-0, but be careful that you don't play a loose point - play aggressive and focus on taking the point from your opponent.