Novak Djokovic produced an impeccable performance to beat Juan Martin del Potro in the US Open final and win his 14th Grand Slam title.
The 31-year-old Serb won 6-3 7-6 (7-4) 6-3 to earn his third triumph in New York and equal American great Pete Sampras' haul of major trophies.
Djokovic, who won Wimbledon in July, will climb to third in the world after back-to-back Grand Slam victories.
Only great rivals Roger Federer (20) and Rafael Nadal (17) have won more.
Argentine third seed Del Potro, 29, was playing his first Grand Slam final since winning the 2009 US Open, having almost quit the game in 2015 because of multiple wrist injures.
A fairytale finish at Flushing Meadows was not to be, however, as former world number one Djokovic's quality shone through.
Djokovic, who was seeded sixth, is one of only eight men to win the Wimbledon-US Open double and has now accomplished that feat for a third time.
The Serb walloped a forehand volley to safety on his first match point, dropping to the floor and spreading out on his back with his arms and legs outstretched in celebration.
After hugging his great friend at the net, Djokovic jumped into his box to celebrate with his wife Jelena and team. Del Potro broke down in uncontrollable tears on his chair.
"It is not easy to speak right now," Del Potro said on court. "I'm sad because I lose but I'm happy for Novak."
After the controversy surrounding Serena Williams' defeat by Naomi Osaka in Saturday's women's final, a high-quality match between two of the top male players ensured tennis was once again the talking point.
|Most Grand Slam titles - men's singles|
|20||Roger Federer (Swi)|
|17||Rafael Nadal (Spa)|
|14||Novak Djokovic (Ser), Pete Sampras (US)|
|12||Roy Emerson (Aus)|
Djokovic continues renaissance to blunt Del Potro
Djokovic had a barren spell between winning the 2016 French Open, where he completed the career Grand Slam, and his fourth triumph at Wimbledon in the summer.
Struggling physically with an elbow injury and seemingly suffering mentally after what he described as "personal problems", he went eight Slams without reaching the semi-finals until Wimbledon.
His performances at the All England Club indicated he was back close to his best and he has shown the same shot-making, stamina and steeliness at Flushing Meadows.
Djokovic, who struggled with the New York humidity in the first two rounds, did not drop a set from the third round onwards.
The Serb had not faced a big server like Del Potro in his run to the final and showed all of his remarkable retrieving skills to frustrate his opponent.
Before the final, Del Potro had seen 41% of his serves unreturned in the tournament.
That figure dropped to 17% in the first set as Djokovic wore him down in some long rallies.
Djokovic had not threatened Del Potro's serve until the eighth game of the match, clinically taking his only break point as the Argentine buckled first.
Del Potro said he felt many of his shots would have been winners against players other than Djokovic.
"I was playing at my limit almost all the time, looking for winners," he said. "But couldn't make them because Novak was there almost every time.
"I took the risks with my forehand because it was the only way to beat this kind of player. My mistakes were because of his level.
"Novak is too fast. His defence is good. It is really difficult to beat a player like Novak."
|Novak Djokovic's 14 Grand Slam titles|
|Australian Open||2008, 2011, 2012, 2013, 2015, 2016|
|Wimbledon||2011, 2014, 2015, 2018|
|US Open||2011, 2015, 2018|
Djokovic keeps pro-Del Potro crowd quiet
Del Potro has a fervent support at the US Open and was backed by a noisy support as thousands of Argentine fans descended on the Arthur Ashe Stadium wearing their national colours of light blue and white.
It made for a partisan atmosphere in the biggest tennis stadium in the world and, with the roof closed because of rain, led to a cauldron of noise.
At times it resembled a football match rather than a tennis match.
"You can win or lose a trophy but the love of the crowd is even bigger than the tournament and that's what I got. It will be in my heart for the rest of my life," Del Potro said.
Djokovic occasionally seemed annoyed by the support with the noise as British umpire Alison Hughes had to constantly plead with the crowd to remain quiet during points.
The atmosphere ignited again in the second set when Del Potro broke back to level at 3-3, before Djokovic silenced them with a courageous hold - after a 20-minute game lasting 22 points and in which he saved three break points to level at 4-4.
That proved to be the key moment in the match.
It enabled Djokovic to go on and take the second-set tie-break following four unforced errors from Del Potro's forehand - including one on set point.
From that point a Djokovic victory looked inevitable and, after Del Potro wiped out a final-set break at 3-1 in the following game, the Argentine produced a double fault to give Djokovic another chance for a 5-3 lead.
Trying to force the issue, he hammered a backhand wide and Djokovic broke before serving out for victory.
Despite defeat, world number three Del Potro remained proud after an achievement he never thought would have been possible during his injury hell.
"I never gave up when I had the wrist problems," he said.
"I got here to the final after nine years which is amazing because this is my favourite tournament on tour."
BBC tennis correspondent Russell Fuller
It was after watching Pete Sampras win Wimbledon - while sitting in his parents' pizza parlour as a six-year-old - that Djokovic decided tennis was the sport for him.
He has rarely looked so ecstatic in his moment of victory: falling on to his back on the same court where his idol won his 14th and final Grand Slam 16 years ago.
Djokovic won with his customary elastic defence, and regular forays to the net. He was just a little better than Del Potro at the key moments - especially in a 95-minute second set, where he saved three break points in an eighth game which stretched to eight deuces and 20 minutes.
This time last year Djokovic was injured and uncertain about his future direction. Six months away from the Tour helped him rediscover his motivation and appreciate just why he wanted to continue.
He has been the dominant player of the summer and could now end the year as the world number one. It has been a remarkable turnaround from a man who now threatens to dominate the men's game once more.