Marcos Baghdatis just won the Vancouver Open a couple of weeks ago. The biggest difference between Baghdatis and most of the players in the draw was his ability to stay calm under pressure. Not only mentally but physically. There were many times during his matches that he was in trouble and he just looked like you knew he would find a way. When he needed a big passing shot on a pressure point he was relaxed during the shot and came up with goods when he needed it most. When coaching high performance players, make sure the player "performs" when they need it most. Look at their muscle tension during their shots, not just the stroke pattern.