Nottingham Forest striker Taiwo Awoniyi was rushed to hospital for emergency surgery on an abdominal injury, according to reports on Monday.
The Nigeria international suffered the injury when he collided with a post during Forest's 2-2 draw against Leicester at the City Ground on Sunday.
Awoniyi had stretched in a failed bid to convert Anthony Elanga's cross and tried to carry on playing after receiving several minutes of treatment.
The true extent of the injury was only discovered by Forest's medical staff on Monday and reports said he was immediately taken for the surgery, which was not believed to be life-threatening.
The incident had provoked an angry reaction from Forest owner Evangelos Marinakis, who stormed onto the pitch and confronted boss Nuno Espirito Santo in a bizarre incident after the final whistle.
Marinakis said he was concerned about Awoniyi's condition after he was left on despite Nuno consulting with his medical staff during stoppage time.
It was a disappointing day for Forest, whose Champions League hopes suffered a major blow as a result of the draw with relegated Leicester.
Nuno's seventh-placed Forest are no longer in charge of their own destiny in their bid to appear in the Champions League for the first time since 1980-81.
They sit one point outside the Premier League's top five places, which guarantee qualification for the Champions League, with two games left against West Ham and top-five rivals Chelsea.
Forest are assured of at least a place in the Uefa Conference League, which will see them play European football for the first time since 1995-96.