He had surgery at St Mary's Hospital in London on Sunday evening and was visited by Hull skipper Michael Dawson and three club officials on Monday.

🔶◾️ | Ryan Mason Update https://t.co/0kECZYXqoq pic.twitter.com/0hTVxUo3ci

— Hull City (@HullCity) January 23, 2017

Hull said in a statement: "Ryan has been visited this morning at St Mary's Hospital by club captain Michael Dawson, club doctor Mark Waller, head of medical Rob Price and club secretary Matt Wild.

"Ryan has been speaking of the incident yesterday and will continue to be monitored at the hospital over the coming days where the club will remain in close contact with Ryan, his family and the staff at St Mary's."

Cahill, Chelsea club captain John Terry and assistant boss Steve Holland went to St Mary's Hospital on Sunday evening to check on Mason's well-being.

Press Association Sport understands the trio spent time with members of Mason's family who had attended the game, which was marred by the incident in the 14th minute.

Hull added in their statement: "Ryan and his family have also been extremely touched by the overwhelming support they have received and would very much like to thank all of those who have posted such positive comments both on social media and in the press over the last 24 hours."

Brain injury charity Headway praised the treatment of England international Mason.

Headway chief executive Peter McCabe said: "I was actually at the match and, while it was upsetting to witness the incident, it was encouraging to see the exemplary reaction of the medical teams.

"Headway has been critical of the way in which head injuries have been treated in many high-profile football incidents in recent years, but it is positive to see that lessons appear to have been learned."

Mason received treatment for around nine minutes on the field and later received messages of support from many of his fellow professionals.

Chelsea head coach Antonio Conte expressed hope that Mason would make a quick recovery immediately after the match, prior to news of his operation.

England defender Cahill had been assessed for some time during the break in play as Mason was attended to.

Conte revealed Cahill's half-time condition "wasn't really good", but he was deemed fit to continue after being reassessed by club medics.

Cahill completed the match, scoring Chelsea's second goal 10 minutes from time.

Headway did not reference Cahill in its statement and it is not possible to make head injury assessments from afar.

The charity last September questioned whether concussion protocols were being observed in football, calling for an independent review after an incident involving Manchester United's Anthony Martial.

Headway's concerns surrounded whether rules introduced in August 2014 were being applied, not specifically the treatment of Martial.

The regulations include the employment of a third 'tunnel doctor' to help team medics identify concussions and whether a player is fit to continue.

Headway favours an approach where, if there is any doubt over a player's fitness to continue, they are withdrawn from the action.