During warmups, the South African swimmer tauntingly danced and shadowboxed in front of Phelps, who was forced to endure the display as he sat in the ready room.
Phelps's rage was palpable. As le Clos continued his show of chest puffing, Phelps broke out a game face to end all game faces: the #PhelpsFace, as the Internet quickly deemed it.
NBC caught the whole thing, Phelps's clinched fists and all.
Of course, Twitter was all over the moment, many comparing the hooded, brooding Phelps to Star Wars' Kylo Ren.
The dude ain't fronting, either. In the semifinal, Phelps finished second, and le Clos finished third. Maybe he should just stick to shadowboxing, huh?