Boss Antonio Conte has acknowledged that everyone at Chelsea was "sad" to hear of Ryan Mason's retirement from football.
Last year, Mason sustained a fracture to his skull in a challenge with Chelsea defender Gary Cahill and although the midfielder spent a year attempting to make a return, the 26-year-old announced this week that he had been advised to retire by doctors.
Chelsea have invited Mason to a future fixture at Stamford Bridge, with his parents being season-ticket holders at the club, and Conte has moved to wish the former England international well for the future.
At a press conference, the 48-year-old told reporters: "We are very sad for this bad news. He showed great strength to recover, to try to play again.
"It's a pity because to stop your career at such a young age, it's a pity. We are very sad. The players and the club wish him and his family the best for the present, the best for the future."
Conte has said that Cahill is 'ready' to face Hull when the two teams meet in the FA Cup fifth round on Friday night.