Former England midfielder Carlton Palmer says he has suffered a suspected "small heart attack" while running the Sheffield Half marathon on Sunday.
The 57-year-old was admitted to hospital and kept in overnight for tests and observations.
Palmer, who won 18 caps for his country, said he experienced problems early on, but did manage to finish the 13.2-mile race.
He tweeted tests are still taking place to determine what caused the issue.
Palmer started his senior career at West Brom in 1984 and played for Sheffield Wednesday, Leeds United, Southampton, Nottingham Forest and Coventry City.
Palmer wrote on Monday: "Thank you so much for all the lovely messages.