Former England and Chelsea midfielder Ray Wilkins is in a critical condition in a London hospital.
St George's Hospital told BBC Sport that the 61-year-old is a patient and "his family have asked for privacy".
His wife Jackie is quoted in the Daily Mirror as saying he had a cardiac arrest and the situation is "very bad".
Wilkins, who also played for Manchester United, AC Milan, Rangers and QPR, has been working as a pundit for Sky Sports and Talksport.
Former Chelsea captain Frank Lampard wrote on Instagram: "All thoughts and strength with this man and his family tonight. An absolute gentleman."
Lampard's ex-Chelsea team-mate Didier Drogba posted: "Just found out about the news, be strong Ray Wilkins and family. We blue army are sending you our prayers on this religious day."
Former England striker and Match of the Day presenter Gary Lineker tweeted: "Thoughts are with Ray Wilkins and his family. Rooting for you, Butch."
As a player, Wilkins won the FA Cup with Manchester United in 1983 and the Scottish league title with Rangers in 1989.
He made 84 appearances for England and captained his country 10 times.
Wilkins had spells as manager of QPR, Fulham and the Jordan national team.
He was also Chelsea assistant coach from 2008 until 2010, working alongside Guus Hiddink and Carlo Ancelotti.