Novak Djokovic’s first match at the US Open was a bit of a litmus test for the Serbian legend because he didn’t play a hardcourt warm-up tournament coming into the year’s final Grand Slam. The 24-time Grand Slam champion said he didn’t play the Cincinnati Open because he prefers to focus on the Grand Slams at this stage of his career.

It has been roughly six weeks since Novak Djokovic played a competitive singles match. Rather than take part in warmup hard-court events ahead of the U.S. Open, the 24-time major champion gave himself a breather,

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 US Open, battling through some leg troubles to beat Learner Tien 6-1,