Footballer Phil O'Donnell died of heart failure, his club has said.
The Motherwell captain collapsed as he was substituted during his side's 5-3 defeat of Dundee United on Saturday.
In a statement released by Motherwell Dr Robert Liddle, the club doctor, said: "The post mortem revealed that Phil had suffered left ventricular failure of the heart."
It is understood that the post-mortem examination was carried out on Monday.
The former Scotland, Celtic and Sheffield Wednesday player collapsed towards the end of his club's win at Fir Park and died later in hospital.
His nephew, David Clarkson, who also plays for Motherwell, was on the pitch when he collapsed in the 72nd minute of the game, as he was substituted.
His widow Eileen said she had been left "devastated" by her husband's death, adding that he would want to be remembered as a family man.
Mrs O'Donnell, mother of the couple's four children, visited a makeshift tribute created by fans of scarves, strips and pictures at the stadium on Monday.
The funeral service for O'Donnell will take place in Hamilton on Friday at noon.
The Requiem Mass, at St Mary's Church, Cadzow Street, Hamilton, will be followed by burial in the nearby Bent Cemetery.
