One of the keys to playing winning tennis is to play within yourself. But what does that phrase really mean? Playing within yourself is when you utilize only the shots you can get into the court consistently under the pressure of match play.
Does that mean you should leave that down-the-line backhand you’ve been working on at home the next time you play? Well, ask yourself whether you really own that shot or not. When you do a drill or hit with a teaching professional, you probably hit the ball harder and better than you ever do in a match. Those strokes don't belong to you. They will make you a better player in the long run, but they are not for your use in a match right now. Why? When you're hitting all those great shots in practice or in a lesson, you’re not keeping score so you have no pressure. Also, you're usually getting a clean evenly-paced ball to hit, with similar spin on each shot, so it’s easier to get into a groove. What’s more, we tend not to care if we miss in practice, so we often conveniently forget how many balls we hit out of bounds or into the net. In a match, though, misses are painfully memorable.
A good rule of thumb for playing within yourself is to limit your game to the strokes you can actually get in the court 10 or more times in a row without missing. These strokes are likely to look a lot different than the spectacular ones you make in practice. If you can’t produce that level of consistency on a given shot, don’t try it in a match.