West Bromwich Albion's Jayson Molumby punched an opponent in the face during a pre-season friendly against Mallorca.
The closed-doors match descended into chaos towards the end of the first half, when a spat erupted between Molumby and Mallorca's Samu Costa.
In a video on Reddit, Molumby can be seen carrying the ball before being challenged twice, the second time being a foul by Costa.
As the pair come together words are angrily exchanged, but the row turns to violence with the flashpoint of Molumby sticking his forehead into Costa's face.
Costa retaliates by placing a hand on Molumby's neck, but the 24-year-old Irishman shockingly decides to make a closed fist, and punch Costa in the face.