Rafael Nadal admitted he feared he had blown his chance of a 19th grand slam title when Daniil Medvedev mounted his astonishing comeback in their epic US Open final.

The Spanish second seed led by two sets and a break, but Russian fifth seed Medvedev somehow hit back to level the match and had break points at the start of the decider.

But Nadal dug as deep as he has probably ever had to to secure a dramatic 7-5 6-3 5-7 4-6 6-4 victory in four hours and 50 minutes to move to within one major title of Roger Federer's record tally of 20.

"Did I think I might lose? Of course, when you have break point against in the beginning of the fifth, losing the last two sets, you are in trouble," he said.

"But I really try to avoid this thought. I always believe that I going to keep having chances. That's the way that I approach.

"It's different in his position after two sets to love and break for me, it's human that he had that feeling. But I always was in front of the score until the end. Is difficult for me to think I am going to lose.

"Of course, I was in trouble. But I played a not very good game at the 3-2 of that third set.

"At that moment things looked under control, but then Daniil increased a lot and changed a lot of things."

The turnaround was not just confined to the court, as the crowd also got behind Medvedev.

The hot-headed Russian, playing in his first grand slam final, had previously been public enemy number one in New York.

He had been jeered by those in the stands throughout the fortnight after he flipped them the middle finger during the third round.

After that match the 23-year-old had goaded the paying public, saying the boos had helped him win the match.

Yet when he launched his unlikely counter-attack it was like Rocky in reverse, the fans around a packed Arthur Ashe suddenly chanting his name.

Afterwards Medvedev said to the crowd: "I want to talk about you guys. Earlier I said it in a bad way, now I mean it in a good way. It's because of your energy that I'm here in the final."

He later added: "It was amazing match. It's an amazing story.

"In the third set I was thinking 'OK, in 20 minutes I have to give a speech. What do I say? Something like that.

"So I was like, 'OK, OK, just fight for every point, don't think about these things'. It worked out not bad.

"Was I close to winning? Yes, one set away. I mean, had break points at 5-4. I will remember everything of it.

"I will be disappointed with the result, but I will be happy with the way I played the whole summer, the whole US Open."