Injured opponents are dangerous. I have seen a number of matches won by players with sprained ankles or leg cramps. Injured opponents who are not discouraged tend to feel loose and hit the ball better than usual. For them, the match becomes all upside. They might still win, but a loss, if it occurs, is no longer their fault. And we see from all the natural excuse-making in tennis that people do not so much fear losing itself as much as they fear being personally responsible for the loss. If the injured players lose, it is now the fault of their injuries, not their own inadequacies, and they thus feel less pressure.

You, on the other hand, seeing an injured opponent and thinking you don’t have to do as much with the ball, will tend to change your game, become conservative, and hit your shots worse than usual. Meanwhile, all the pressure is on you. (If you win you get little credit, but if you lose you get the full disgrace of losing to an injury case.)

Against these people it is wise to forget about the injury and play your normal game. Thinking about an opponent’s injury gets your mind involved too much with strategy and not enough with execution. Execution relies on a simple plan, focus on the immediate situation, and keeping emotions under control. Absorbing yourself in assessing the extent of your opponent’s injury in order to change your game and take advantage of it will generally lead you into errors.

What about handling the times you are the injured player? When I was on the tour I rarely lasted more than five or six weeks without having an injury of some kind. The injuries were not usually totally debilitating, but they did limit my performance. I was usually better off with injuries that limited my movement because I could compensate by hitting my shots more severely. I was careful to limit my moves to reduce the risk of further damage. I had to accept that there were now certain moves that I couldn’t make. To compensate, I had to work harder mentally to anticipate earlier where my opponent was going to hit the ball, and on hitting my own shots better.

Once I figured out how far I could push without pain (so as to reduce the risk of further damage), I became determined to play within these limits and forget the injury. I had to accept that I might lose some extra points, but I still felt I could win if I executed well with what I had left. It was particularly important not to dwell on the injury or allow myself to become frustrated because I wasn’t able to make all my normal shots.

It is analogous to the mental adjustments players must make as they age and their capabilities deteriorate. Here they must focus on what they have left and forget about what’s missing. What you can’t do on the tennis court, whether you used to be able to do it or not, is no more pertinent than the fact that you can’t fly.

Putting this all together suggests: 1) If your opponent is injured, focus on your own normal execution rather than the injury; and 2) If you are injured, you can push the injured part within the limits of pain without causing further damage, but you must play hard and smart within those limits. Maximize what you have left and accept with good grace what you no longer can do. Above all, bite your tongue and resist the urge to tell people about your injury.

Allen Fox, Ph.D., is a psychologist, coach, former Wimbledon quarterfinalist and author of Tennis: Winning the Mental Match.