Crystal Palace manager Roy Hodgson underwent tests in hospital on Thursday evening after being "taken ill" during a training session in the morning.
The 76-year-old - who is the oldest manager in Premier League history - had been preparing his team for next Monday's away game against Everton when he became unwell.
A Palace club statement published shortly before 6pm on Thursday read: "Following news that Roy Hodgson was taken ill during today's training session, we can confirm that he is now stable and is currently undergoing tests in hospital.
"Everybody at the club sends their best wishes to Roy for a speedy recovery."
Palace had earlier canceled a press conference that Hodgson was due to speak at.
Hodgson has taken charge of 200 Palace matches across two spells in charge at Selhurst Park.
However, it was reported by the Daily Mail earlier this week that Palace were poised to part company with Hodgson.
Former Eintracht Frankfurt boss Oliver Glasner is said to be a likely contender to replace him.
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