David has a losing H2H against both of them. 2:3 against Roddick and 0:1 against Blake. Roddick just lost, so it is between Tsonga and Blake. Blake has a weakest serve, he is a ballbasher who can be dangerous cause takes the ball early on the rise and with such a pace that is either a nonreturnable one or a way long or wide, plus he is not one of the mentally strongest players. Tsonga on the other hand has great serve, has heavy CCs, he is extremely dangerous at the net (he is hard to pass), he can even play good defense from time to time and can hit a passing shot DTL on silly approach shots, but he is most of the time confused when the opponent steals a net from him. Plus he is not very consistent.
Tsonga is also a little fragile, physically. And now he has played three 3-setters in a row. Add to that the nerves, if he were to make his first Masters final, and on home ground on top of it.
Blake has beaten David in their only match, but generally speaking, David does well against ballbashers. Another case of having to keep the rallies short and not give him any rhythm.
But still, it's Davydenko I'm worrying about most at the moment...