The Nottingham attacker Taiwo Awoniyi collided with the post when he threw himself forward in an attempt to reach a pass from the Swedish national team player Anthony Elanga in Sunday's Premier League match against Leicester (2–2).
The Nigerian is said to have sustained an abdominal injury and been forced to undergo surgery, according to several British media outlets.
Awoniyi, who was substituted in in the 83rd minute, received treatment for several minutes and returned to the pitch, but was clearly affected by the injury. Nottingham had already made all their substitutions and the attacker had to take it easy during stoppage time.
It was not until Monday that it became clear how severe Awoniyi's injury was. The club has not confirmed that he has undergone surgery.