How do you beat someone who is clearly inferior but?

The thoughtful approach to tennis strategy is to create offensive opportunities via the placement of your shots. This could mean moving your opponent to one side and the exploiting the open area or taking advantage (approaching the net and ending the point) of weak returns that are the result of your deep or well placed shots. Richard Katz U.S.P.T.A. / P.T.R.

Patience, patience, patience.

You have to be very patient as Thomas Kendall mentioned above, and then play smart tennis; Use the angles, and keep your opponent off balance by moving him/her from side to side, while holding the center of the court.  Then anticipate the short ball when it eventually comes, which it will do.  Then choose the right shot to end the point.  Stay in control, because as long as you are in control of the point, you should win it.

dont play them at their own game. you need to make them feel uncomfortable by taking them outside of their comfort zone by making them play shots they dont want to play. use slice, get them to the net, target their weaker groundstroke. dont let them get into a rythme and dont show that you are tired or dont like their tactics as they will do it even more.

Play your own game

Use your strengths to move your opponent from side to side

To set up the point so you can put the ball away into the open court

for the

You can find fragments of one of bolletieri's DVD's on youtube.

Search for "Tennis lessons%3A Building points and tactics", these clips have some useful tips on how to play against certain styles, without changing your game but rather putting some tactics in to play.

I would suggest not to try and make every shot a winner but to open up the court and wait for a good oppurtunity. If you try to finish the rally with every shot, you will only get more frustrated when it isn't working out and dwell over the previous shot rather than thinking about the next.

So the question is, "How do you beat someone who is clearly inferior but just keeps the ball in play?"

I apologize for responding with another question.  How do you determine if your opponent is clearly inferior?  I think if you are sure that your opponent is inferior, you would already know what to do.  Otherwise, your question would suggest you are at a loss as to how to play your opponent because your opponent is playing you effectively.  If this is the case, your opponent may just be as good if not better than you are.