Yep, her doubles partner and good friend. Thats why it's so interesting. If they weren't partners, i'd say that Slava would easily take Vania out in 2 without hesitation. But the fact that they are partners means that they know each others game, and it might be close.
I think Del Potro will go to the semis in this tournament.
I think if he gets past Djokovic in the quarters, then he will make the final. I don't think Ferrer,Isner, Tisparivic (howevber you spell it) would beat Del Potro. The winner of the Del Potro and Djokovic quarter is a shoe in for the final imo