Nottingham Forest striker Taiwo Awoniyi underwent surgery for an abdominal injury on Monday after he clattered into a post during their 2-2 Premier League draw with Leicester City a day earlier, Forest said in a statement.
Substitute Awoniyi rejoined the game after receiving treatment but was limping around for the last 10 minutes.
"Everyone at Nottingham Forest sends their best wishes to Taiwo," Forest posted on X.
Forest owner Evangelos Marinakis expressed frustration over Awoniyi not being substituted, with manager Nuno Espirito Santo saying the Nigerian international was left on due to a misunderstanding between the coaching and medical departments.
Forest, a point behind fifth-placed Chelsea, visit West Ham United on Sunday.