A very effective tactic used to wrong-foot your opponent is aiming the ball behind him. What does aiming the ball behind your opponent mean? It is when you aim the ball back to the same place where your opponent struck right before.
Remember that in tennis that after you strike the ball you have to recover and be ready to cover the higher percentage shot. This usually means you have to side-shuffle away from the place you just struck the ball at unless you hit the ball cross-court (since if you aim it CC, the return would be a CC back to you). So when is the most effective time to execute this tactic? The best time would be when your opponent hits a down-the-line shot because now he has to go and recover to the higher percentage shot leaning towards the other side.
When executed correctly, your opponent will be in trouble having to immediately change directions and cover more space. There will also be many cases where your opponent will be completely thrown off balance by your shot that he won’t be able to reach the ball in time, if executed perfectly. Maybe your opponent could be completely wrong-footed and stumble.
This tactic does not only apply to groundstroke exchanges. You can most definitely apply this to your net game as well – hit an approach shot and hit your first volley towards the same spot. This tactic is a must-add to your arsenal!
Check out this video (At 7:13) of Kei Nishikori incredibly displaying this tactic against Rafael Nadal!:
Also check out this video (At 1:53) of Tommy Haas demonstrate hitting the ball behind Roger Federer: