schedulu match today and my bet
Johnson S. (Usa) - Murray A. (Gbr) - Andy murray win
Del Potro J. (Arg) - Bautista-Agut R. (Esp) - Delpotro win
Monfils G. (Fra) - Nishikori K. (Jpn) - Monfils win
Nadal R. (Esp) - Bellucci T. (Bra) - rafael nadal win
The matches now are getting harder to pick a winner but I think you have picked the right ones to win but I would not be surprised if Nishikori beats Monfils and you just never know Bellucci may even beat Nadal as he will have the home crowd cheering him on. There have already been some big upsets so far and this would be one of them.