This follows a two-year Slam drought for the 31-year-old Serb, who suddenly is tied with Pete Sampras for the third-most major trophies by a man, trailing only Roger Federer's 20 and Rafael Nadal's 17.
"I was very, very disappointed with my performance that day", Djokovic recalled Sunday, explaining that he went hiking in the mountains in France to clear his head after that setback.
Djokovic is behind Rafael Nadal and Roger Federer, with the trio occupying the top three spots in the rankings again for the first time in more than three years.
"Pete Sampras is one of the biggest legends ever to play the game", Djokovic said. "But I love you too, guys", he told the crowd.
And yet, after the events that unfolded in Saturday's women's final at Flushing Meadow, no one - not the players, the officials, administrators, the fans or the sport itself - emerged as a victor.
As a snapshot of Sunday night's match, the eighth game of the second set served quite well. Ahead of the final, Del Potro had fired 68 aces during the tournament, winning 82 percent of his first serve points.
A five-day hike in the Alps transformed and inspired struggling Djoko for Flushing MeadowsWhen Novak Djokovic's year got off to a less-than-ideal start, the Serbian set off on a five-day hike in the French Alps that proved transformative.
Djokovic's most hard opponent this tournament has been the heat and humidity, so Sunday's cool and wet conditions, resulting in the roof being shut on Arthur Ashe Stadium, were perfectly to his liking. "But for me, I felt like I really had to focus during this match because she's such a great champion, and I know that she can come back from any point".
Just like last night's women's singles final, the match was played under closed roof with rain in NY.
"But, at the same time, there was always part of me that imagined and believed and hoped that I can get back to the desired level of tennis very soon". "I had to figure out early in my career, when I was losing most of the big matches @ the Grand Slams against them, what it takes for me to actually kind of improve and develop my game to be able to challenge them, to be able to start winning against them when it matters the most".
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.
The game went so long that when it ended, with Djokovic holding to 4-all, spectators began leaving their seats, perhaps thinking it was time for a changeover, even though it wasn't. While del Potro put up a tough fight, the native of Serbia found a way to gut it out in the end.
"I thought of tennis, thought of the emotion that tennis provokes in me in a way".
It was only the second set dropped by the Argentine at the tournament.
"Cecchinato made me realise a lot of things after that loss to him in Roland Garros", said the 14-tim Grand Slam champ. "It will be in my heart for the rest of my life".