Novak Djokovic was not happy when the referee slapped him with a warning at the Shanghai Masters.

Facing Alex Michelsen in his opening game, the world No. 4 lost the shot clock at the start of the second set and received a timeout.

He immediately questioned referee Mohamed Lahyani during the call, but was reminded that the clock was now running automatically.

Djokovic is back in action for the first time since helping Serbia beat Greece in the Davis Cup three weeks ago. The 37-year-old had a tough test when he faced Michelsen on Saturday and suffered an early break.

He stormed back to win the first set in a tiebreak, but still didn’t seem too happy with his level when he served in the second set at 1-1. After sending the ball wide, the 24-time major champion screamed to himself in frustration.

And things got even worse when he received a timeout warning when he was 15:30 behind. Djokovic let the ball bounce away and turned to the referee.

“Why are you doing this man? “Why are you doing this man?” he asked.

Lahyani reminded him: “It’s out of my hands.” The Shanghai Masters uses the new automatic shot clock, which starts three seconds after the end of the previous point. The players then have 25 seconds to serve.

This means that the referee has no discretion to delay the start of the countdown due to a long rally or crowd noise. And commentator Nick Lester said Lahyani felt guilty about warning Djokovic.

“It was almost like he didn’t want to do it. He said it in a whisper, didn’t he, Mohamed Lahyani? “He knew what was coming,” he noted.

Co-commentator Arvind Palmer responded: “It’s not ideal, is it? But it enforces the rules.”

“That’s half the problem, the rules aren’t always enforced. Starts automatically, takes more than 25 (seconds), what should you do?”

Djokovic didn’t seem too bothered by the warning. He fired an ace to make it 30-30 and promptly held serve. The world number 4 is not the only one struggling with the new automatic shot clock.

When it was screened at the Queen’s Club in June, Carlos Alcaraz spoke out against it, calling it “crazy” and “something bad.” He also threatened to talk to the ATP.

The Spaniard struggled again last week when he was called up for the China Open in Beijing. After being booked in his opening game, he told the referee: “I’m always very fast, I never get warnings. You gave me two in one set and it’s impossible to play tennis like that.”