The new film “Challengers” is very steamy, as has been made clear by the trailers featuring Zendaya as a young hotshot tennis player — and later, coach — who is the focal point of a love triangle completed by co-stars Josh O’Connor and Mike Faist. It is playfully dramatic, in the trademark fashion of Italian director Luca Guadagnino (“Call Me by Your Name”). And perhaps most surprisingly, it is actually full of tennis.

No, really. Gameplay is vital to the drama. In fact, it is the drama. Zendaya’s character, Tashi Duncan, informs her male suitors early on that the power of tennis isn’t in self-expression, but in the dynamic formed between you and the other player. This philosophy informs the confidence Tashi lords over lesser athletes, the grief she suffers after a knee injury puts an abrupt end to her playing career and the quiet rage seething beneath her calm exterior as she pivots to coaching from the sidelines.

It also contributes to the tension that burgeons between those suitors, Patrick Zweig (O’Connor) and Art Donaldson (Faist), as they transition from being best friends and doubles partners to romantic rivals and, years later, singles opponents. In adulthood, Tashi coaches Art.

“There’s something so charged about a tennis match,” said screenwriter Justin Kuritzkes (who happens to be married to Celine Song, writer-director of another love triangle in last year’s romantic drama “Past Lives”). “It’s such an intimate relationship that you’re having with this other person. You’re spending the whole match trying to get in their head.”

None of this would work if the actors weren’t believable as athletes. Kuritzkes could write endless praise of Tashi into the script, but Zendaya needed to seem like she could actually be one of the best. O’Connor and Faist needed to look like they were batting tennis balls at each other with all of their might. But Zendaya was relatively new to the sport before production, as was O’Connor. Faist was the only one who had any real experience, and that dated back to high school. (He’s 32.)

Mike Faist, left, and Josh O’Connor in “Challengers.” (Niko Tavernise/Amazon/Metro Goldwyn Mayer Pictures)

In came Brad Gilbert, the ESPN analyst and former tennis player who now coaches U.S. Open winner Coco Gauff. Back in 2021, he was just someone who had 20 singles titles to his name, who decades ago ranked No. 4 worldwide among singles players, and who had coached players including Andre Agassi and Andy Roddick. So, you know, “a tennis guy” — as he says his daughter, a Hollywood assistant, phrased it in a pitch to her boss, producer Amy Pascal, who was looking for an expert to consult on the film. (Does this make him a “nepo dad”?)

“They sent me the script, my wife Kim and I read it, and then within two or three days, we were literally on a Zoom meeting … with Luca, Amy and Rachel [O’Connor, another producer],” Gilbert said, referring to a meeting that took place in December 2021. “They didn’t have any of the tennis points really written. … How were we going to play these points?”

Brad Gilbert coaches Coco Gauff in preparation for the U.S. Open in August 2023 in New York. The ESPN analyst says preparing the “Challengers” actors “got me ready for Coco.” (Matthew Stockman/Getty Images)

Brad Gilbert with wife Kim at the Los Angeles premiere of “Challengers” on April 16. ( (Chris Pizzello/Invision/AP)

Gilbert and a colleague from ESPN, researcher Miki Singh, joined Kuritzkes in going through each of the tennis points played in the script. “Every forehand, every backhand, every one of those,” the screenwriter said. They were painstaking in their process, with Gilbert critiquing the feasibility of each action. Then, they took the list to tennis rehearsals to the Boston area, which stood in for New Rochelle, N.Y., where much of the film takes place. Professional and semiprofessional athletes played through the points in the presence of Guadagnino and cinematographer Sayombhu Mukdeeprom, who built their shot list off these practices.

“We could really treat the tennis sequences like we were making a martial arts movie or something — it was fight choreography,” Kuritzkes said. “We could treat it like a place where story was happening. … These characters are able to communicate with each other through tennis, through action, in a way that they can’t communicate with their words.”

The actors had clear instructions. Now, they had to execute.

While Josh O’Connor was out of commission early on, filming another project in Italy, Gilbert set Faist up with tennis and lifting guidance to help him gain back the weight he had lost while shooting Steven Spielberg’s “West Side Story.” Kuritzkes wrote Art as a more aggressive player, according to Gilbert, who described the character as “more patterned, like a [Federer], like a Pete Sampras with a classic one-handed backhand.”

Tashi “was supposed to be this killer,” per Gilbert, but the script didn’t get much more specific than that. Gilbert worked with Zendaya in Los Angeles, accompanying her to observe real players. They spent several hours at a Pepperdine vs. Arizona State men’s match and a few weeks later watched women’s players at Pepperdine vs. UCLA. “I think that really helped her to understand it more, watching it live and seeing a college match,” Gilbert recalled. “Like, ‘This thing is a little more intense than I thought.’”

Brad Gilbert, serving at the Volvo Tennis Classic in 1987, won 20 singles titles during his pro career and reached a career-high singles ranking of No. 4 in the world in 1990. (Bud Symes/Allsport/Getty Images)

Production was intense, too: “We found out really quickly that shooting tennis is incredibly time-consuming and difficult,” Kuritzkes said. “You have to shoot everything four times. You have to shoot with the actors, with the doubles, with the ball, without the ball.”

Some of the tennis didn’t even make it on camera. Gilbert remembered a gutting moment in which O’Connor finally accomplished the tweener, or a between-the-legs shot, that he had been struggling with for weeks — only to discover it hadn’t been filmed. “The odds of him making that were one in a billion,” according to Gilbert. “I was so gutted for him.”

There’s a reason tennis so often serves as a metaphor for life. O’Connor’s character, Patrick, knows even better than the other two that things don’t always pan out the way you hope. As Tashi and Art soar, Patrick descends into the doldrums of an aging player — that is, until an opportunity arises for him to get even, kick-starting him into motion. “You never know what’s going to happen,” Gilbert said of life as an athlete. But he helped the actors step into that volatile space with gusto, noting that the young folks “got a kick out of my energy.”

“Doing what I did [on ‘Challengers’] got me ready for Coco,” he said. “My wife says life imitates art.”