Hull have announced Ryan Mason suffered a fractured skull in the Premier League match at Chelsea and is in a stable condition after surgery.
They continue to say that he is expected to remain in hospital for the next few days following the operation.
The 25-year-old former Tottenham player and Chelsea’s Gary Cahill collided in Hull’s box after 14 minutes of the Tigers’ 2-0 loss at Stamford Bridge.
Hull boss Marco Silva was awaiting an update on the player’s status.
“Ryan Mason at this moment is staying in the hospital. I don’t know more news about this,” Silva said.
“I hope nothing special, nothing serious, but at this moment the player stays in hospital. The doctor stayed with the player in hospital. I wait for news.”
Both medical teams rushed to the scene as referee Neil Swarbrick stopped play.
Cahill quickly returned to his feet and readied himself to return to the action. He completed the game and scored Chelsea’s second goal.
Mason was in hospital by then, having received treatment for around six minutes on the field before departing on a stretcher, while receiving oxygen. David Meyler replaced him.
Chelsea head coach Antonio Conte said: “Everyone at Chelsea wants to wish for him the best.
“It was a bad accident with Gary and, I must be honest, after the first half also Gary wasn’t really good. He decided to continue the game.
“It was very bad this accident. Everyone at Chelsea, we hope to see him very soon on the pitch and to recover very soon.”