Novak Djokovic’s night is already off to a bad start.

The 16-time Grand Slam champion was captured on video getting into it with a fan during his warmup session before facing American Denis Kudia in the third round of the US Open at Arthur Ashe Stadium on Friday night.

Djokovic was getting ready to serve when he stopped – catching his toss on the way down – before walking over to the fence to confront a fan, who may have said something he didn’t like. After the discussion, Djokovic walked away and kept pointing at the fan.

“I’ll come find you,” he said. “Trust me, I’ll come find you.”

Djokovic will get a chance to take his frustrations out on the court against Kudia.