Rafael Nadal has only gotten stronger as the US Open has progressed

Rafael Nadal says he is finally happy with his play at the US Open, defeating Juan Martin del Potro to reach the final.

The top seed dropped a set in the second and third rounds but cruised from there until the semifinals, where he dropped the first set before romping to victory.

Nadal has lifted his game during the tournament.

"I was playing so-so at the beginning of the tournament, and I have been playing better and better every day," the 15-time Grand Slam champion said.

The Spaniard added that a good performance was required against Del Potro, who was coming off a win against Roger Federer.

"Today was the day to play the best match of the tournament since that moment, because I gonna play against the toughest opponent in that moment, and that opponent, as I said before, coming with big confidence," he said. "I wake up today and 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. A lot of the matches he played this tournament have been a tough one. But at the same time, I think I played a solid match."

Nadal plays Kevin Anderson in the final.