Leicester City chairman Milan Mandaric says defender Clive Clarke is making a good recovery after collapsing at half-time during a game on Tuesday.
Clarke is on loan at Leicester from Sunderland
Clarke, 27, was taken ill during the interval of their Carling Cup tie at Nottingham Forest and spent Tuesday evening "stable" in hospital.
Mandaric said: "Encouragingly, Clive is improving and he's quite comfortable. It's important he just gets better."
The game was abandoned and it will now take place on Tuesday 18 September.
Forest were leading 1-0 at half-time through Junior Agogo, but both clubs decided to call the game off after Clarke was taken ill.
The Leicester and Forest officials reacted magnificently in the circumstances
Sunderland chairman Niall Quinn
Clarke's agent Gary Mellor said the player was treated with a defibrillator in the dressing-room.
Clarke had regained consciousness by the time he was taken to the nearby Queens Medical Centre in an ambulance.
Mandaric added: "It's a sad thing when you see a young man collapsing and getting down on the floor.
"It wasn't something that anyone can accept easily but I think the most important thing now is that he gets out of hospital and gets on with his football."
Foxes boss Martin Allen paid tribute to their medical staff for their quick treatment of Clarke at the City Ground.
"I must say head physio Dave Rennie and sports scientist Damien Doyle were absolutely outstanding in coping and dealing with what was a traumatic and difficult situation," said Allen.
"We are lucky both members of staff were on hand at such a difficult and testing time."
Clarke's agent Mellor told BBC Radio Stoke he did not know when the left-back would be released from hospital.
"Clive is sitting up and talking and he is going to have more tests at the hospital on Wednesday afternoon," said Mellor.
"They won't give us any idea as to when he will be released. They don't want to tell us anymore until they know exactly what happened.
"It appears Clive's heart stopped twice and mouth-to-mouth didn't work so the paramedics had to use a defibrillator.
"His family are very upset, especially after what happened with the Sevilla player Antonio Puerta dying recently. We just hope he's going to be OK."
Leicester chief executive Tim Davies said all the club's thoughts were with the Republic of Ireland international and he also paid tribute to Forest.
"When Clive went into the dressing-room he collapsed and was very seriously ill," said Davies.
"This is the first time we are aware of anything happening to Clive. He was taken away in an ambulance to hospital and he did offer a few words in the ambulance.
"Our thoughts and prayers are with Clive and his family, we hope he makes a speedy recovery.
"I would like to say a big thank you to Nottingham Forest for dealing with the matter so fast and to [manager] Colin Calderwood, [chief executive] Mark Arthur and [chairman] Nigel Doughty for calling off the match so quickly.
"We want to apologise to the fans who came here but I am sure they understand sometimes serious injuries are more important."
Sunderland chairman Niall Quinn and manager Roy Keane also sent their best wishes to Clarke.
"The Leicester and Forest officials reacted magnificently in the circumstances," said Quinn.
"Our thoughts and prayers are still very much with Clive and his family and we wish him a speedy recovery."
Keane added: "He's one of our players and fingers crossed, please God, he'll be OK. We wish him well."