"Of course he can", said Del Potro when asked if Djokovic can claim the record over Federer who is nearly six years his senior.
The Serb, who was back in the final for an eighth time and contesting his 23rd Grand Slam final - the third most in men's tennis history - was serving exceptionally well and earned a break in the eighth game after showing tremendous patience before successfully serving out the set.
Djokovic faced similar questions about whether he'd ever get back to another major final with his elbow woes, but after his triumph at Wimbledon in July, and with the more heralded - and older - Rafael Nadal and Roger Federer showing signs of slowing down, another reign of the Djoker looks very real in men's tennis.
Amid increasing noise between points and serves, which prompted frequent interventions from chair umpire Alison Hughes, the previously assured Djokovic - who missed the tournament previous year due to an elbow injury - appeared agitated.
Britain's Alison Hughes, the second woman to umpire a U.S. Open men's singles final, kept a low profile as the two former champions went to work.
The sixth seed had suffered in the ferocious heat and humidity through the early days of the season's final Grand Slam but dropped only two sets for the tournament and none since the second round.
Carlos Ramos defends officiating of Serena Williams in US Open final
Umpires are forbidden by contract from speaking out to the press, but one retired ump was able to voice the views of his brethren. Williams, a six-time US Open champion, has since been fined $17,000 by the United States Tennis Association for the violations.
Djokovic was thrilled to match Pete Sampras with a 14th Grand Slam title, but he said it's Federer and Nadal who have made him the player he is.
It is his 14th Grand Slam title, which ties him with Pete Sampras for third on the all-time major singles titles list behind Federer's 20 and Nadal's 17. "He will be the favourite to win on Sunday", Del Potro said. He knows he is one of my friends on Tour and knows he is one player I want to see win titles.
Federer lost in the fourth round in NY, while Nadal retired from his semifinal against del Potro because of a bad right knee.
A costly double-fault from Del Potro - his first of the match - and a series of errors saw Djokovic move one game away from victory and after three hours and 16 minutes he completed the job with an unstoppable overhead smash and then lying flat on his back on the court in celebration.
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)". "I'm glad that Novak is the champion". "We all go through our emotions, especially when you're fighting for a Grand Slam trophy", he said. "Novak has everything to make records in this sport", said the Argentine. "Today I really am". He depended on his hometown friends, a group of whom have been in NY throughout the fortnight to lead cheers in Arthur Ashe Stadium, and worked his way back to the final at his favorite ATP Tour event.