Novak Djokovic, back in the United States Open final in style, had just hugged his wife, Jelena, and doffed his cap theatrically as some of his friends bid him farewell for the night.
As he headed for his postmatch news conference inside Arthur Ashe Stadium to discuss the challenge of facing Juan Martín del Potro, someone shook Djokovic’s hand and said, “Well done, Mojo Man.”
Djokovic laughed, which had been a rare postmatch occurrence in the difficult, strange days when the mojo was gone.
“I felt deep down that he was a little bit burned out after winning so much for years,” said his former coach, Boris Becker, who once struggled with his own motivation after reaching the summit of men’s tennis.