In a rollercoaster decider on a quiet Arthur Ashe Stadium, Thiem – playing his fourth major final – eventually closed out a 2-6 4-6 6-4 6-3 7-6 (8-6) victory.

The Austrian 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, needing more than four hours in the first US Open final to be decided by a fifth-set tie-break.

There were six breaks of serve in the final set, with Zverev – playing his first major final – giving up a 5-3 lead before Thiem also failed to serve it out at 6-5.

But as both players looked tired and with Thiem, 27, seemingly cramping, he managed to hold his nerve the better of the two to win a first major.

Zverev, who came from two sets down to beat Pablo Carreno Busta in the last four, was this time on the front foot from the outset and needed only 30 minutes to take the opener.

The German, 23, broke his apparently anxious opponent twice in the first set and raced into a 5-1 lead in the second.

Thiem raced forward to volley at the net and earn one break back, but Zverev served out the set and quickly went about making progress in the third.

Yet another poor service game concluded with a wayward stroke under little pressure, seemingly bringing the finish line into view after just 90 minutes of play.

But Thiem finally showed some resilience and, despite seeing one opportunity pass with an agonising miss at the back of the court, he tied the set again, then staying patient before another gain took the match to a fourth as the wobbling Zverev went wide.

Thiem's level improved as both held comfortably to begin the fourth set, although the Austrian was passive as he squandered two break points in the sixth game.

But Thiem would take his next chance, grabbing a 5-3 lead when Zverev double faulted and then sent a forehand into the net, before closing it out to force a fifth set.

The pair traded breaks to begin the decider as both showed nerves before Thiem recovered from 0-30 in the sixth game and fell behind again in the eighth, Zverev breaking for a 5-3 lead, only to give that advantage straight back with a poor game when serving for the title.

Serving at 30-30 in the 10th game, Thiem produced two spectacular forehands, the first a rocket down the line before a passing shot.

Thiem, looking the more tired and perhaps cramping, broke for 6-5 when Zverev sent a forehand well long, but he too failed to serve it out after a brief visit from the trainer.

Zverev's 15th double fault gave Thiem a 5-3 lead in the tie-break before the latter squandered two match points, including one from a weak second serve from the German.

But Thiem would finally close out victory, falling onto his back behind the baseline as Zverev pulled a backhand wide to complete a dramatic finish.

STATISTICAL BREAKDOWN
Thiem [2] bt Zverev [5] 2-6 4-6 6-4 6-3 7-6 (8-6)

WINNERS/UNFORCED ERRORS

Thiem – 43/55
Zverev – 52/64

ACES/DOUBLE FAULTS

Thiem – 8/8
Zverev – 15/15

BREAK POINTS WON

Thiem – 7/13 
Zverev – 8/18

FIRST SERVE PERCENTAGE

Thiem – 62
Zverev – 64

PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE

Thiem – 68/48
Zverev – 70/41

TOTAL POINTS

Thiem – 162
Zverev – 159