Playing against a very tall player might seem scary, but if you implement the right strategies, you can do it. First, I'm going to outline what he probably does well. Next, I'm going to outline your game-plan.
 
Keep in mind that very tall players have a wide wingspan. With a little leaning and reaching, he can often cover about 7 feet without taking any steps at all. Very tall players usually smash well and can power through most lobs.
 
So what should you do? First, remember that he likely covers the wings well. If you play corner to corner, they will be able to easily reach those balls. So typically, the strategy is to play against the middle - the transition point between backhand and forehand. Even if the tall guy can return it, it will probably be a much weaker ball.  Keep in mind that the middle might be in a  slightly different position with offense and defense.  For example, might cover 50% of the table with backhand when blocking and only 30% of the table with backhand when looping.  Early in the first game, make a mental note of his transition point and hit there often! The other strategy is to play extreme angles. As I mentioned, he plays the corners by reaching and often doesn't move well.  By playing to his extremely wide backhand or forehand, you will probably get a winner.  He will try to reach instead of moving.
 
 
Remember
1. Placement is the key
2. Find the transition point for both offense and defense
3. Focus on hitting his transition point
4. Occasionally, go for the extreme angle