Dominic Thiem described his US Open success as a dream come true after rallying from two sets down to claim his first grand slam crown in New York.

After three runners-up appearances in major finals, second seed Thiem finally broke through by outlasting Alexander Zverev 2-6 4-6 6-4 6-3 7-6 (8-6) at Flushing Meadows on Sunday.

The Austrian, who overcame a slow start, became the first player to rally from two sets down to win a US Open final in the Open Era, and first since 1949.

Thiem is also the first man born in the 1990s to win a grand slam after prevailing in more than four hours in a rollercoaster final on Arthur Ashe Stadium.

"Definitely I achieved a life goal, a dream of myself, which I had for many, many years," Thiem told reporters after his memorable comeback against the fifth-seeded German. "Of course, as a kid, as well, when I started to play tennis. But back then it's so far away.

"Then I got closer and closer to the top. At one point I realised that, wow, maybe one day I can really win one of the four biggest titles in tennis.

"I put a lot of work in. I mean, I dedicated basically my whole life until this point to win one of the four majors. Now I did it. That's also for myself a great accomplishment.

"I mean, it's by far not only myself, it's an accomplishment from all my team, from all my family. I guess also today is the day where I gave back huge amount of what they did for me."

Thiem lost a thrilling Australian Open final to Novak Djokovic earlier this year, having fallen short in the 2018 and 2019 French Open deciders to Rafael Nadal.

"When I first realised that maybe one day I could really win a major was when I first broke into the semis of Roland Garros, when I broke into top 10," said the 27-year-old Thiem, who never gave up hope against Zverev. "From that moment on I dreamed about it. I thought that it's maybe realistic.

"Back then I thought my biggest chances by far are on clay. But then the end of last year somehow changed a lot of things when I won Beijing, when I won Vienna, when I played the great Nitto ATP Finals. Then I realised that my game is suiting the hard courts really well.

"Of course, since I'm working with Nico [Massu], we improved my game on hard court a lot. Also changed my mind that many shots are working great on that surface. So I think my best major until now US Open, I played in Australia. Now it's not for me that big surprise anymore that it's not the French. At the end it doesn't matter to me. Main thing is that I have one of these four now."

As Thiem basks in his first major triumph, attention quickly turns to the upcoming French Open in Paris.

The rescheduled French Open is due to get underway on September 27 at Roland Garros amid the coronavirus pandemic.

Asked about the transition from hard to clay courts, two-time French Open runner-up Thiem said: "I think physically I'm going to be fine, 100 per cent. I'm going to have enough time to recover from all the troubles I had.

"But the question is how I'm going to do it with the emotions mentally. Obviously, I've never been in this situation. I achieved a big, big goal. Well, I don't know how I'm going to feel the next days.

"At the same time it's going to be or I expect that it's going to be easier for me now in the biggest tournaments because I had it in the back of my head that I had a great career so far, way better career than I could ever dreamt of, but until today there was still a big part, a big goal missing.

"With this goal achieved, I think and I hope that I'm going to be a little bit more relaxed and play a little bit more freely at the biggest events."