Hull City midfielder Ryan Mason has suffered a fractured skull in a clash of heads with Chelsea's Gary Cahill and is in a stable condition after having surgery at a London hospital.
The incident occurred during the first half of Sunday's (Monday AEDT) 2-0 English Premier League defeat at Chelsea.
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Mason is expected to remain in hospital for the next few days, the EPL club announced.
"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 Hull statement said.
"A further update will be issued tomorrow."
@HullCity carried Ryan Mason off but @ChelseaFC left Gary Cahill in the game. Irresponsible IMO @ChrisNowinski1 pic.twitter.com/jkEFPzMD3C
â Andy Campbell (@AndyCampbell16) 22 January 2017
Get well soon Mase!! Thoughts are with you and your family, stay strong!!! @RyanMason pic.twitter.com/HLU2tN5irN
â Gareth Bale (@GarethBale11) 22 January 2017
Both medical teams rushed to the scene as referee Neil Swarbrick stopped play at Stamford Bridge.
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.
Chelsea coach Antonio Conte said: "Everyone at Chelsea wants to wish for him the best."
AAP