• Keane says 'everything is about control and power' • Former United midfielder rates Brian Clough as best manager

Roy Keane believes Sir Alex Ferguson is still trying to exert "control and power" at Manchester United despite retiring as manager in the summer. The Irishman, who was Ferguson's midfield driving force for the club between 1993 and 2005, says the Scot has a "massive ego" and rated his former boss at Nottingham Forest, Brian Clough, as the best manager he had worked with.

United have endured a difficult start to life under Ferguson's successor David Moyes, having lost three Premier League games at Old Trafford already this season to sit ninth in the table.

Keane said of Ferguson, now a director at United: "Everything is about control and power. He's still striving for it now even though he's not manager. There's massive ego involved in that."

Keane, who left United in 2005 after a fall-out with Ferguson, was speaking in an ITV4 documentary called Keane and Vieira: The Best of Enemies which airs on Tuesday night concerning his rivalry with the former Arsenal captain Patrick Vieira.

He said that his relationship with the former United manager is now "non-existent". The Irishman even took issue with Ferguson praising him in his recently released autobiography for "covering every blade of grass" in the 1999 Champions League semi-final second leg against Juventus.

Keane added: "Stuff like that almost insults me. I get offended when people give quotes like that about me. It's like praising the postman for delivering letters."

Keane admitted he had cried in his car when his United career came to an abrupt end over a candid interview he gave to the club's in-house television station criticising his team-mates. He said: "Of course I was upset: I did shed a few tears in my car for about two minutes. But I also told myself I had to get on with my life. I walked out with nothing, I had no club lined up and I was injured.

"I told David Gill I had been injured playing for Man United. I could have played for Manchester United easily for another couple of years."

Keane laughed off the furore surrounding the infamous MUTV interview and said he felt the row between Ferguson and then club director John Magnier over the stud rights to racehorse Rock of Gibraltar had to have had a "negative effect" on the club.

Keane said: "I managed the dressing room: that was my job. If people didn't think [the Rock of Gibraltar row] had a negative effect on the club then they are in cuckoo land."

Keane said Ferguson's strongest trait was his "ruthlessness", while labelling "loyalty" his biggest weakness. And now Ferguson has retired, Keane revealed he and his son have season tickets at Old Trafford.