[BobK]

I wrote this up before I read the replies. Seems logical to me.

Dave said the opponent will continue to play the same way and you know them very well. Since you know them well, you must already be using your best strategy against them.

It is unlikely for you to be less skilled than your opponent if you're 5 matches up.
Worst case is your about equal(+-very little). That makes each of the following matches a 50-50 coin flip.

.5 ^ 5 = .03125. So you have a 3.125% chance of losing the tournament. If you are actually the better player, that figure would be even smaller.

I don't think I'm going to alter my strategy in an attempt to gain part of about 3.125% or less. I'll stick with the one that got me there.