Nadal, 31, is the decided favorite as he pursues his third U.S. Open title and 16th Grand Slam championship in his 23rd Grand Slam final. His course here hasn't been entirely smooth but he has gradually raised his level of play. On Friday he said he awoke in a good frame of mind before he faced Del Potro. "I say to myself, 'Today is the day that I'll play. I need to play with the right energy and I need to increase the level of my game,' and I know that," Nadal said. "A lot of times I know that and it didn't happen, but [on Friday] it happened."