Tashi (Zendaya), a tennis player-turned-coach, has taken her husband, Art (Mike Faist), and transformed him from a mediocre player into a world-famous Grand Slam champion. To jolt him out of his recent losing streak, she makes him play a “Challenger” event — close to the lowest level of tournament on the pro tour — where he finds himself standing across the net from the once-promising, now burnt-out Patrick (Josh O'Connor) : his former best friend and Tashi’s former boyfriend.