Do you level down to your opponent's level, or...

Say, you are playing ping-pong with a colleague, or racket with your boyfriend, or chess with your cousin.
Only you notice that you are much better in that specific game of sport.
Will you level down, to make the match more balanced, or you hold on to your high(er) level and ‘kill’ the other person (because finally you found someone that you can beat)?
So how do you deal with these situations and what reasoning is behind it?
Examples of when you had this happening to you are welcome, of course.