Sunderland chairman Ellis Short fired Martin O'Neill over the phone on Saturday.
The Daily Mail says Short and Oâ€™Neill had been in conflict over the former Aston Villa managerâ€™s January buys and spoke on the telephone hours after the game on Saturday, when Oâ€™Neill was told his contract was being terminated.
He and his wife, Geraldine, then travelled to the clubâ€™s training ground to clear his desk. The couple, who had moved into a house in Durham, are expected to return to their family base in the south.
The former Leicester and Celtic boss had been in charge for 15 months after he was appointed by Short as Steve Bruceâ€™s successor, weeks after Niall Quinnâ€™s departure as club chairman.