I'm going to have to go with unders for the games here, I think. I can see Federer maybe taking a set, but even 4 sets could well stay under the 41.5 game limit. I'll leave it there, as the game's about to start anyway, so:
Federer v Nadal
under 41.5 games @ 1.833 3pts
GL all, and here's hoping for a decent final
