Hull City midfielder fractured his skull during the clash against Chelsea as he clashed heads with Chelsea defender Gary Cahill.
Mason, 25, had to go through an emergency head operation in London’s St.Mary’s hospital on Sunday evening.
“Ryan is in a stable condition and expected to remain in hospital for the next few days,” said a Hull statement.
“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.”
Mason joined Hull from Tottenham last August for a club-record undisclosed fee.