The American has since received backing from the WTA and now Djokovic, who beat Del Potro 6-3 7-6 6-3, has weighed in with his thoughts on the controversial argument.
Djokovic is into his eighth final in NY where he was champion in 2011 and 2015.
He missed last year´s tournament with an elbow injury which sent his career into a mini-crisis.
For world number three Del Potro, it was a heartbreaking experience coming in just his second Slam final, nine years after he was crowned US Open champion before a long battle with wrist injuries pushed him into depression and to the brink of retirement.
"I just feel like, as Serena said in the closing ceremony, Osaka deserves to have her moment".
Djokovic though fought off the noise and Del Potro's challenging tennis to eventually take the second in the tiebreak. But supported by a dozen or so friends from back home, whose "Ole!" choruses rang around the arena, he climbed up the rankings to a career-high No. 3 by thundering his 100 miles per hour (160 kph) forehands and 135 miles per hour (215 kph) serves.
The third seed mounted a last-gasp offense in the third set, which even got a racquet clap from Djokovic.
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It was a magnificent night of tennis from both players, where Djokovic's athleticism, court coverage and tennis brains came out triumphant against Del Potro's big serve and forehand.
Never was that more apparent than the game that stood out on this evening: with Djokovic serving while down 4-3 in the second set. It's a tough thing for a chair umpire to deal with.
But seemingly temporarily distracted by del Potro's supporters getting louder, not to mention the world No. 3's better play, he was broken back for 3-3. Later, after winning a point, Djokovic put that finger to his ear, as if to say, "Who are you cheering for now?!"
While Streep was beside herself, Jerry Seinfeld had more of a skeptical look. But Djokovic was in no mood to hang around, winning the last three games to clinch the crown.
Osaka has never been to Nemuro, but she is said to have expressed a desire to visit the place where her mother was born, although her grandfather commented, "She'll be busy and I guess it will be hard for her (to come soon)".
"When I had the surgery on my elbow I could truly understand what Juan Martin was going through".
Where is Novak Djokovic vs Juan Martin del Potro US Open 2018 men's singles final match?
'Cecchinato has made me realize, a lot of things after that loss to him in Roland Garros', Djokovic admitted. 'I was very, very disappointed with my performance that day.
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