Every have a match where you were "In the Zone," where the ball seemed to slow down, and you could almost do no wrong? This is relative, of course; an intermediate player "In the Zone" isn't going to compete with a professional, but he would dominate against his normal peers. Here's a good article on the topic: Being in the Zone – Sport’s Holy Grail.
There are many articles and books about getting into this "Zone," including ones listed in the Sports Psychology listing I have here. (Dora Kurimay, a table tennis champion, can help with this, and another good one for this specifically is Michael Lardon's "Finding Your Zone" – he's also a former table tennis star.)
However, there's a pre-requisite to getting into the zone that has nothing to do with sports psychology. You cannot be "In the Zone" if you are not comfortable with what your opponent is doing. If your opponent does something that you are having trouble with, then you either have to keep him from doing it, or adapt to it. Being "In the Zone" means reacting automatically to what your opponent does, and you can't do that if you are uncomfortable with what he does.
Suppose your opponent has a weird inside-out forehand that looks like it's going one way, but goes the other. You can't really be in the zone against something like this if you are constantly going the wrong way. This means you have to adapt to what he's doing. Sometimes this means letting him do the shot simply so you can adjust to it. The more you see it, the more you adapt to it, and the more you can react to it. Once you are able to react to it properly, you are ready to be "In the Zone."
The worst thing you can do is to lose a match, and afterwards realize you never adapted to what the opponent was doing. This usually means you only faced it when you weren't ready for it, and so didn't adapt. Sometimes it's best to play right into it, so you know when it's coming, so you can make the adjustment.
Here's an example. Many years ago I had to play a 2200 long-pipped blocker, i.e. a "push-blocker," with no sponge under his long pips. Unfortunately, there was no one at my club who played like that or with that surface, and so it had been years since I'd played anything like it. Before the match I realized that if I didn't adapt to his no-sponge long pips, I could lose. But more importantly, I realize that the only way I could lose was if I didn't adapt to his long pips. Why? Because I knew that once I adapted to them, I would be "In the Zone," and he would have nothing to threaten me with. So instead of playing to win points, right from the start all I did was rally into his long pips. We had lots of long rallies, and we battled close, but I didn't worry about the score until near the end of the game. Around 8-all, I went after his forehand and middle, and won three straight. The second game was a repeat – again, lots of long rallies. Near the end of that game I figured it was time – and then I played to win the points. I was now completely comfortable against his pips, and I was now "In the Zone." I won easily the rest of the way.
There are many other examples. Does your opponent have a very strong backhand? Perhaps play into it intentionally a few points, challenging his strength as you adapt to it so that you'll be comfortable against it when you have to, and then go back to your game. Does he have a spinnier loop then you are used to? Play into it a few times so you can adapt to it, then go back to your game. Does he push heavier than you are used to? Serve backspin into it so you can attack a few so you can adapt. And so on. Sometimes you might challenge the strength and then go to the weakness. For example, after challenging the opponent's strong backhand so you can adapt to it, perhaps counter-attack to his weaker forehand side. You get the best of both worlds – you adapt to his strength, and you play into his weakness.
None of this means you should continue to let your opponent play his strengths – you should normally use tactics to avoid them. But if you are going to have to face them, then it's better to adapt to them than not to do so, and adapting to them allows you to enter "The Zone," and suddenly his strengths, when he gets to play them, won't be so scary.
So next time you have a match, quickly find out what your opponent does that gives you trouble, and do what it takes to adapt to it. Then play your best game, where you now can be "In the Zone" against whatever your opponent throws at you.