London - Hull City midfielder Ryan Mason was in a "stable condition" in hospital on Sunday following an operation on a fractured skull, his club said after a sickening clash of heads with Chelsea's Gary Cahill,
The pair collided 14 minutes into Premier League leaders Chelsea's eventual 2-0 win at Stamford Bridge.
Medical staff from both clubs sprinted out to attend to the two players, with referee Neil Swarbrick halting play for more than five minutes while on-field treatment was administered.
But while central defender Cahill returned to his feet and indeed scored Chelsea's second goal with a header as he completed the match, the unfortunate Mason left the field on a stretcher while receiving oxygen before being taken to the nearby St Mary's Hospital in west London.
Several hours after the final whistle a Hull statement said: "The club can confirm that Ryan Mason sustained a skull fracture in our fixture at Chelsea this afternoon.
"He was taken to St Mary's Hospital where he has undergone surgery.
"Ryan is in a stable condition and is expected to remain in hospital for the next few days.
"Everyone at the club would like to express their sincere thanks for the excellent and swift care given to Ryan by both the Accident and Emergency department and Neurosurgery Unit at St Mary's Hospital.
"A further update will be issued tomorrow (Monday)."
Immediately after the match Marco Silva, the manager of second-bottom Hull, said he hoped Mason had avoided a serious injury.
"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."
Chelsea head coach Antonio Conte said all those connected with the London club hoped Mason enjoyed a speedy recovery.
"Everyone at Chelsea wants to wish for him the best," he said.
"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."
Watch incident below: