NEW YORK -- Novak Djokovic thinks he came up with a way to get Serena Williams back on the tennis tour: Dare her to do it. A night after Williams stunned the tennis world by showing up to help induct rival Maria Sharapova into the International Tennis Hall of Fame, Djokovic said he thought that was “a beautiful moment.”

Novak Djokovic may still be going strong at 38, holding his own against the new generation led by Carlos Alcaraz and Jannik Sinner, but even he knows he can’t play forever. As the last active member of the legendary “Big Three,” every tournament he enters feels like a reminder that tennis is inching toward the end of an era.

Djokovic, 38, beat Tien, 6-1, 7-6, 6-2 to improve to 19-0 in US Open first-round matches, tying Roger Federer for first all-time. But he labored with low energy, a nasty blister on his right big toe and Tien’s level, especially in the second set.