Fabio Fognini has branded his third-round victory over Rafael Nadal at the US Open as "incredible".

The Italian came from two sets behind to beat Nadal in five at Flushing Meadows, hitting 70 winners during the third-round clash.

Fognini has said that he needed to be at his best to overcome Nadal, who had never before dropped a two-set lead in a Grand Slam.

"Well, with Rafa you have to try that (hitting 70 winners), because otherwise if you run - he start running at the beginning and you finish at the end of the week. It's not easy," Fognini told reporters. "Right now I can't tell you something more because it was something incredible that I did today."

Fognini will take on 18th seed Feliciano Lopez in the fourth round on Sunday.