WIMBLEDON, England—Few players in tennis history have ever had a tactical repertoire like the Novak Djokovic playbook. It runs so deep that it’s impossible to pick out a single signature move. 

He is the master of the two-handed backhand down the line. He is incomparable when defending deep in his own court. And, in the tightest moments of the biggest matches, Djokovic has perfected the art of bending time to his advantage: he uses the bathroom break.

“You mainly use this moment to reset yourself mentally, changing your environment,” Djokovic said at this year’s French Open. “Even if it’s a short break, you can have a few deep breaths and come back as a new player.”

Now into the semifinals of Wimbledon and chasing a season sweep of all four majors plus Olympic gold, Djokovic is applying bathroom resets to devastating effect. During this year’s French Open alone, he did it twice, including once midway through his come-from-behind victory in the final. 

But Djokovic, 34, isn’t just running to the bathroom more because he’s getting older. Strategic pauses have been a key tactic for him throughout his career.

A Wall Street Journal analysis that surveyed scoresheets, live blogs, video, and anecdotal reports of his matches found a dozen instances where Djokovic has taken bathroom breaks during matches at major tournaments since 2013. All but one of them came in tense matches that went at least four sets. And in 10 of the 12 cases, he took the next set immediately. That gives Djokovic, who has won 78.6% of his career sets at Grand Slams, an 83.3% success rate following a trip to the restroom.

Novak Djokovic changes his shirt during a break in play at Wimbledon.

Novak Djokovic changes his shirt during a break in play at Wimbledon.

Photo: glyn kirk/Agence France-Presse/Getty Images

“He wants a moment for himself, some peace and quiet,” his former coach Boris Becker said during the 2019 Wimbledon final, when Djokovic outlasted Roger Federer in five. “He will want to gather his thoughts to reset for the third set.”

Sitting on the border between legitimacy and cynical gamesmanship, the bathroom break is only controversial to the player not taking it. The letter of the law in men’s tennis allows for two comfort breaks in a five-set match—and only in between sets. (Players are occasionally allowed to leave the court mid-set when the call of nature threatens to cross into medical emergency.)

The lack of a time limit leaves them open to abuse. In 2019, the Women’s Tennis Association attempted to address the issue by cutting the number of allowable bathroom breaks to one from two in their best-of-three set matches.

Djokovic has made it clear very few bathroom breaks actually involve using the bathroom. More often, he simply changes his shirt and maybe shouts at himself in Serbian a little. The goal is to halt his opponent’s momentum, like a catch-your-breath timeout in basketball. And this is the part that drives his rivals crazy. “Don’t worry about him,” Andy Murray grumbled during the match when Djokovic took a medical timeout at the 2015 Aussie Open. “He does it all the time.”

Stefanos Tsitsipas, his opponent in the French Open final last month, was more bewildered than upset. Djokovic was down two sets to none in barely 90 minutes when he trudged off court.

“I don’t know what happened there, but he came back, to me, like a different player, suddenly,” Tsitsipas said after Djokovic reeled off the next three sets. “He played really well, he gave me no space…I felt he could read my game suddenly.”

Carefully timed pit stops have kicked off plenty of Djokovic comebacks. But perhaps none stands out to him like the break he had no choice over.

Novak Djokovic uses a towel during a break in play at Wimbledon.

Novak Djokovic uses a towel during a break in play at Wimbledon.

Photo: glyn kirk/Agence France-Presse/Getty Images

Djokovic was playing the quarterfinals of the 2010 Australian Open against France’s Jo-Wilfried Tsonga when the heat got the better of him. Bleary-eyed and hyperventilating, Djokovic felt so ill in the Melbourne furnace that he had to run off the court mid-set and dive into the bathroom, where he vomited into the toilet. Djokovic resumed the match and limped to defeat in five. 

That moment, he wrote in his autobiography, “was probably the lowest point in my career…My body was broken. My mind was broken.”

Djokovic credits that incident in part with his shift to a more holistic approach to health, which features a gluten-free diet and a spine-bending yoga program. That was now 11 years and 18 Grand Slam titles ago.

The greats have been deploying the tactical nature break forever. At the 2010 Aussie Open, Federer once used one of his two allotted trips to the bathroom because the sun was in his eyes and he wanted to burn some time, hoping the angle would change. “I never take toilet breaks, but I thought, ‘Why not?’” he said at the time.

Djokovic tends to battle more than the sun and his rivals, mostly because tennis fans love to hate him. When he plays Grand Slam matches against the likes of Federer and Rafael Nadal, he turns into a wrestling heel, the interloper who arrived after both of them. And even against the rest of men’s tennis, he’s used to hearing plenty of cheers for the other guy. No one makes underdogs more popular than Djokovic.

“Sometimes I’m able to just kind of let it go and keep the focus on what matters for me and on the match,” he said at Wimbledon. “Sometimes I get distracted.”

The solution, as ever, is a trip to the men’s room to collect his own thoughts and, just as importantly, leave his opponent to stew with theirs. It’s all part of Djokovic’s psychological warfare—just ask Portugal’s Joao Sousa, who got so fed up of waiting for Djokovic to return at the 2018 U.S. Open that he lost his temper at the chair umpire.

“I was asking him why he’s taking so long,”  Sousa said afterward. “There is no limit for a toilet break. So I think it’s a rule that it’s a little bit messy.”

Djokovic won in straight sets.

Novak Djokovic takes a rest during a break in action at the French Open.

Novak Djokovic takes a rest during a break in action at the French Open.

Photo: Aurelien Morissard/Zuma Press

Write to Joshua Robinson at Joshua.Robinson@wsj.com