Photo: Alex Goodlett/Getty Images

Frances Tiafoe, the best American teen in the men’s game, hasn’t taken down any giants yet, but every few months he gets quite close. Back at the U.S. Open, he took literal giant John Isner to a fifth-set tiebreak, and last night in Acapulco, the 19-year-old took Juan Martin del Potro to a third-set tiebreak before losing 6-4, 3-6, 7-6 in the first round of the Mexican Open.

Both players like to take it fairly easy on their backhands—content to push it back safely or slice it—but they take huge, lunging cuts on the forehand side. Delpo’s forehand, a scarily flat thwack, is one of the game’s best-known offensive weapons; Tiafoe’s forehand, which has more topspin to it, starts in an unabashed loop and ends with a whole lot of arm action. If that motion looks unusual, that’s because it’s homespun: Tiafoe, the son of a tennis center custodian, was largely self-taught in his formative years, wandering the grounds, devising his own drills, and beating up a practice wall.

The matchup of big forehands produced some lengthy, watchable rallies, as well as decent proof that Tiafoe, the youngest player in the top 100, is nearly ready to test the elite baseliners in the men’s game.

It also showed off some of his Tiafoe’s absurd athleticism, as seen in a sneaky volley to pluck a deep Delpo forehand out of the air. His fast feet and soft hands were reminiscent of another shot on the run last fall.

A visibly tired Tiafoe fell apart in the tiebreak, going down 7-1, but if the first two hours of this match were was any indication, he’ll find that breakthrough win soon.