Novak Djokovic improved to 19-0 in the first round of the U.S. Open, battling through some leg troubles to beat Learner Tien 6-1, 7-6 (3), 6-2 on Sunday night. Djokovic had his hands on his knees multiple times in the second set and received treatment on his right big toe after it.

Novak Djokovic looked tired. He looked hurt. And at times Sunday night, he just looked old. Djokovic overcame all that and improved to 19-0 in the first round of the U.S. Open, battling through some leg troubles to beat Learner Tien 6-1,