West Ham co-owner David Gold is in hospital with pneumonia.
The 76-year-old attended the Hammers' FA Cup tie with Manchester United on Saturday, but his daughter Jacqueline confirmed on Tuesday night via Twitter that he had been taken ill.
She said: "Have taken my father into hospital. I think he's learnt a very harsh lesson - not to go to football with bronchitis, now has pneumonia!
"[Gold] is currently being assessed will update you as soon as I can."
On Wednesday afternoon she added: "Just to update you my dad had a good night but is still on strong medication for his condition.
"He is still very poorly but in good hands and obviously won't be at the game on Saturday."
In March 2011 Gold was admitted to hospital with cholangitis and septicaemia but recovered fully.
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