I don't think either player is going to get broken much, so we're certainly in for a couple tiebreaks. Even if Federer outplays Nadal, Nadal's gotta get 1-2 tiebreaks and probably win one or two on top of that. So:
7-6, 7-6, 6-7 is a guaranteed Over victory.
Basically this bet becomes a bet that "neither will win in straight sets". A straight sets victory, at the least, would look like:
6-4, 6-4, 6-4 = 30
Can you imagine either player losing worse than this?
If we get at least one tiebreak in the first 3 sets, and neither wins in straight sets, we're golden:
7-6 6-4 4-6 = 33 and then we just need one 6-4 set after that.
7-6, 7-6, 6-7 is a guaranteed Over victory.
Basically this bet becomes a bet that "neither will win in straight sets". A straight sets victory, at the least, would look like:
6-4, 6-4, 6-4 = 30
Can you imagine either player losing worse than this?
If we get at least one tiebreak in the first 3 sets, and neither wins in straight sets, we're golden:
7-6 6-4 4-6 = 33 and then we just need one 6-4 set after that.