The disappointment on Sunday belonged to a teary Del Potro who was back in a Grand Slam final for the first time since the big Argentine won his one and only title at Flushing Meadows in 2009.
Del Potro hailed the victor after losing in his first final since winning the Wimbledon Title in 2009.
His 6-3, 7-6 (4), 6-3 defeat to the Serbian was not the fairytale outcome he had imagined.
Del Potro sensed blood and broke for 3-1 as Nadal struggled for movement. But then he was broken in his next game.
Potro had three more chances in the eighth, all saved by Djokovic in a marathon 20- minute game.
But with a third US Open title to go with the Wimbledon crown he secured in July he has matched American Pete Sampras on 14 Grand Slam titles and there is little doubt that the 31-year-old is one of the sport's greats.
In the absence of any representative body to speak for tennis officials, it fell to the ITF to say what should be evident to all: despite Williams's repeated insistence that Ramos owes her an apology, he was just doing his job when he penalised her a point and a game during Saturday's tumultuous women's US Open final.
Amid increasing noise between points and serves, which prompted frequent interventions from chair umpire Alison Hughes, the previously assured Djokovic - who missed the tournament past year due to an elbow injury - appeared agitated.
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Del Potro was looking at having to become the first man since Pancho Gonzales in 1949 to win the U.S. title from two sets down.
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"I was so close to the desired level, and then I completely underplayed that match". There has been a first-time victor in four of the past six Grand Slam tournaments, and 20-year-old Naomi Osaka added to the eclectic mix by becoming the first Japanese to win a Major. I will keep playing tennis for a few more years.
"Are you insane?!" was Osaka's reply.
She posed with her trophy at Top of the Rock Observation Deck at Rockefeller Center.
Djokovic, the 2011 and 2015 US Open champion, largely controlled proceedings in a high-quality final. "We all go through our emotions, especially when you're fighting for a Grand Slam trophy". They hadn't even dropped a set over that run until Babos and Mladenovic got them in the first set on Sunday.
The Spaniard player called a medical timeout after three games of the second set to have the right knee rebandaged.
Four easy holds later and it was onto a tiebreaker that decided the second set, and ultimately the course of the match as Djokovic capitalised on several bad errors from his opponent to win it 7-4. The team had previously won the Miami Open in March.
"Got everything thrown at her: big bombs by Serena, the crowd, the drama".
'I don't know the answer.
The magnitude of her achievement was almost drowned out by the chaos in the aftermath of Williams's tirade against the chair umpire.
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.
But instead of that victory proving a launchpad for a sustained challenge at the Grand Slams, Del Potro battled wrist injuries which required four surgeries. "And so, so happy to be playing the final against this magnificent idol".