PHOTO BY NIKO TAVERNISE / MGM

Early in “Challengers,” Tashi Dunan (Zendaya) gives a coy definition for her chosen sport, tennis.

“It’s a relationship,” she says, leaving out an adjective before the noun — “intimate,” perhaps, is implied. She’s saying that tennis opponents are linked, physically and spiritually, in a moving, rhythmic give-and-take.

Getting the picture yet? This is a respectable website, so I’m not sure how much more explicit I can be.

“Challengers” is the sweat-soaked, tawdry story of one such relationship, a long-simmering love triangle between elite players — both on and off the court, a distinction that makes little difference to Duncan. She’s become enamored with a pair of lifelong friends and frequent on-court rivals, Patrick Zweig (Josh O’Connor) and Art Donaldson (Mike Faist); she’s equally charmed by their athletic physiques, their obsequious affection and their on-court prowess.

We see the sordid history of these upwardly mobile athletes in glimpses, from their first meeting as elite-level junior players to an unlikely showdown much later in their careers. Duncan, it seems, first chose Zweig — after promising to give her number to whomever won a championship match — only to reject him after he expressed disinterest in her professional advice. After a career-ending injury, she became coach and later wife to Donaldson.

Donaldson and Duncan became celebrities, while Zweig became a journeyman at best. The power couple, their faces emblazoned on building-sized billboards, dismiss their former third as an overgrown child. The script, by novelist and playwright Justin Kuritzkes, subtly interrogates what arrested development actually looks like, particularly in the neverland of professional sports.

Director Luca Guadagnino, no stranger to unconventional relationships (“Call Me By Your Name,” “Bones and All,”) fixates on the film’s rhythms — the pounding of the racquet, the drumming of rain, the way scenes speed up and slow down, a series of dazzling mid-game camera angles. It is, not accidentally, a frantically paced film, rising and falling like a heartbeat.

Is it pulp? Is it art? It’s both and neither. “Challengers” is a good, grown-up night at the movies, where beautiful people kiss and fight in equal measure. That’s entertainment. And sports. And … again, let’s just call it “intimacy.”

My Rating: 9/10

“Challengers” opens in theaters on April 26.