Hopefully there is one shot at least you are partially on the way to owning, and I would go with that as much as you can. I would not recommend trying to mix it up and vary your shots unless you want a very frustrating evening.
One day you are going to have a full repetoire of shots you can hit consistently, with depth and accuracy, but until then you need to do the boring bit of hitting a shot over and over until it is not going to be a source of errors.
Sounds like you are not going to outhit or hit winners against this player. I would choose a spot to serve to and just go for that all evening. Choose a spot for service return and do the same. You can even hit groundies all evening to the same spot.
Ok, your opponent will know what you are going to do, but s/he will have to make all the play, and you can just concentrate on doing your thing. When you have those shots grooved in matchplay conditions, then add a few more and then a few more. Before long you will be in possession of a Federer like range of shots.....
Make a note of a few things to do and read it at change overs.
A few ideas:
Breathe from the stomach - no point in being in a state of panic.
Breathe out slowly and purposefully during the stroke.
Turn your shoulders, yes right round till you think they won't go any further.
Keep your head down until long after contact
Bend your knees - just enough so that your feet disappear.
Take your racket back as soon as your opponent hits the ball, NOT when it bounces on your side of the court. (If you want to be very technical about it, take it back parallel to the baseline when you are moving to the ball and then all the way back as far as a your arm with a slight bend will allow you so you still have some fluidity. I am not a great believer in taking the racket so far back that you opponent can see the face of the racket unless you have God given talents).
Take the ball early in the proper sense - hit the ball well in front of you, short backswing, long followthrough. If your opponent has such classy strokes, just make use of all the work they are doing and minimise your effort.
Make your opponent beat you, don't beat yourself by making unforced errors. Do what you are confident of doing and don't try for things you don't own. If your opponent hits you off the court and your best makes no impression on them, that is why they are better than you. But you will have got just that little bit further down the road to being the player you want to be.
And there will be a moment in the match where your opponent's level dips a little, hopefully to below your rocksteady grooved play. Just a matter of waiting. It will come, often at the most surprising times like when they are serving for the match.
When I have a choice of going for a screaming winner but go for the percentage shot that my opponents chews up I feel good knowing I chose the right shot, and don't get frustated being beaten by a better player.
