Peter Reid watches as Keane storms away from the field of play (RossKinnaird/GettyImages)

After a fierce contest between the players throughout the match, referee Uriah Rennie produced the red card after Keane appeared to strike his former Republic of Ireland team-mate in the face.

But Ferguson, who has also backed Keane amid the furore caused by the serialisation of his autobiography, was critical of both Rennie and McAteer as he played down the nature of the clash.

The United boss said: 'I do not think he swung an elbow - he put an arm across his face. If the referee deems it a sending-off I do not know what we can do.

'The player McAteer went down quickly which is disappointing. We will see what the offence is but my gut feeling is it was very soft.'

Ferguson told Sky Sports News: 'The ref did not act (on a previous incident in the match) when Keane was kicked in the back as seen on TV.

'I think if people see it then they will judge it - it was an innocuous incident.'

Keane's former international colleague Niall Quinn shook hands with him as he left the pitch in a gesture which sparked an angry reaction from Ferguson, but Black Cats boss Peter Reid admitted that he did not see the incident which sparked the red card.

'I didn't see it,' he said. 'You know me, if I'd seen it, I would comment on it.

'When it gets high tempo and people start losing their heads, as a manager you want your players to keep their discipline. Luckily, they did.

'You have clashes in football matches - I think I had one or two in my career and I think Roy Keane and Jason McAteer have. It usually blows over.

Reid was pleased with his team's recovery from a poor start as debutant striker Tore Andre Flo equalised with 20 minutes remaining following Ryan Giggs' 7th-minute opener.

'For 25 minutes, I didn't think we wanted to be part of a tremendous game because we stood off and watched them,' he said.

'You can show Manchester United respect, but if you give them that much time and space, you're going to get murdered.