John McEnroe was quick to bring Mariano Navone back down to earth just moments after his career-best win.

The 25-year-old Argentine player defeated 24-time Grand Slam winner Novak Djokovic in a five-set opening round U.S. Open match on Sunday night. As Navone was signing tennis balls to send into the Arthur Ashe crowd, McEnroe said: “You’ll be playing your second roung on Court 21. We wish you the best.”

The comment pointed to the reality that Navone’s second-round match will likely be far from the bright lights of Arthur Ashe Stadium.

“He’s going to have to try to play with that effort and intensity, but enjoy the moment young man,” he added on the ESPN broadcast.

The former American tennis pro turned anaylst received backlash from tennis fans for the comment and others during the match.

“McEnroe’s entire attitude towards Navone was despicable from the jump,” one X user commented.

“McEnroe was disrespectful to Navone from the beginning. In the first set he says how great of an opponent Navone is for Djokovic because he won’t challenge him at all,” another said before writing McEnroe is a “tired act.”

“[Chris] Eubanks or [John] Isner would be significantly better on the call moving forward,” the same X user added.

Navone earned the 7-6(5), 5-7, 4-6, 6-2, 6-1 win over a struggling Djokovic, who exited in the first round of a Grand Slam for the first time since the Australian Open in 2006.

The 2026 U.S. Open is now the first Grand Slam to not feature a single member of the “Big 3” — Roger Federer, Rafael Nadal and Djokovic — in the second round since Roland Garros in 2003.

“It means a lot,’’ a smiling Navone said. “It is a dream come true, certainly.”

Navone could be seen estatically celebrating with his team after the victory that ended only minutes before midnight local time.

He will go on to face either Matteo Berretini or 41-year-old Stan Wawarinka in the second round in Queens.