Novak Djokovic will get a couple of extra days to rest up from his various ailments.

The defending champ moved on to the third round of the U.S. Open when his opponent withdrew before their match Wednesday. The top-ranked Djokovic had faced a potentially tricky matchup with Jiri Vesely, who defeated him last spring in their only meeting.

But a couple of hours before they would have taken the court, Vesely pulled out because of left forearm inflammation.

Djokovic has been dealing with some arm troubles of his own. He said he hurt his left wrist a few days before the start of the Olympics, where he lost in the first round to Juan Martin del Potro. That injury also kept him from playing at Cincinnati.

Then in Monday's four-set victory over Jerzy Janowicz, Djokovic received treatment on his right arm during the opening set. He repeatedly winced and shook out the arm, his serves far slower than usual.

After dropping a set in his opening match at a major for the first time since 2010, Djokovic didn't want to talk about what was going on with his arm.

Vesely beat Djokovic 6-4, 2-6, 6-4 on clay in Monte Carlo in April. At the time, Djokovic hadn't lost a completed match since November.

Vesely, 23, is currently ranked 49th. He's coming off his best performance at a major, a run to the round of 16 at Wimbledon that included another win over a top-10 player in Dominic Thiem.

Djokovic will face 51st-ranked Guido Pella or No. 61 Mikhail Youzhny in the third round Friday.