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.

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.

Novak Djokovic is on a race against time to clinch his 25th Grand Slam title. Since winning his 100th career title at the Geneva Open, the Serbian has only shown up for the Grand Slams.