Nadal escaped two set points against him in the opening set before cruising to a 7-6 (6), 6-4, 6-1 semifinal victory over the No. 24-seeded Berrettini at Arthur Ashe Stadium. The second-seeded Nadal never faced a break point in the match.
"You don't want to be in a tiebreak against a player like Matteo," Nadal said during his on-court interview. "I was a little bit lucky, no? I survived at that moment and ... after that, the match completely changed."
Nadal, 33, has lost only one set at this year's U.S. Open. With the victory, he has reached the final of a Grand Slam singles tournament for the 27th time in his career. He holds an 18-8 record in those finals, trailing only Roger Federer (20) for the most Grand Slam singles trophies in a career.
Nadal will challenge No. 5 seed Daniil Medvedev on Sunday for the men's U.S. Open title.
Medvedev advanced to his first major final after defeating unseeded Grigor Dimitrov 7-6 (5), 6-4, 6-3 on Friday. The 6-foot-6 Russian hadn't made it past the fourth round at a Grand Slam event until this year's U.S. Open.
Medvedev, who eliminated Federer in a five-set quarterfinal match, avoided dropping the first set and went on to claim his 50th victory this year, the most by any player in 2019.