Lionel Messi has been fined an undisclosed amount by Major League Soccer after striking Philadelphia Union midfielder Quinn Sullivan during a heated 2-2 draw between the teams Wednesday.

The 39-year-old Inter Miami forward was penalized by the MLS Disciplinary Committee for violating the league’s policy prohibiting contact with an opponent’s face, head or neck. The incident occurred in the 101st minute at Subaru Park in Chester, Pennsylvania, deep into second-half stoppage time.

Messi appeared frustrated after Sullivan seemingly caught him with an elbow following a challenge. As the players exchanged words, Messi reached behind Sullivan and made contact with the back of his head or neck with an open-handed slap.

The confrontation did not immediately result in a card, but the league reviewed the incident and announced the fine Friday.

“The MLS Disciplinary Committee has fined Inter Miami CF forward Lionel Messi an undisclosed amount for violating the league’s policy regarding hands to the face/head/neck of an opponent,” the league said.