O’Neill is under fire from some sections of the media after his side’s poor start to the season, though they moved out of the relegation zone with what was only their third victory of the season on Tuesday, 3-0 over Reading.
Having taken over at the Stadium of Light just over a year ago, the Northern Irishman makes his first visit to United with Sunderland on Saturday; he has previously brought Aston Villa and Leicester teams to Old Trafford.
“There was a question to him last week which was absolutely ridiculous,” Sir Alex said at his Friday press conference.
“A journalist or a TV guy asked him if he still had self-belief. Martin O’Neill has won three titles with Celtic, he’s taken them to a UEFA Cup final, he’s been at Aston Villa, he’s been at Leicester City… what a silly question.
Martin O'Neill's managerial record against Manchester United:
Sunderland (Dec 2011 - present)
League: Lost 1
Aston Villa (Aug 2006 - Aug 2010)
League: Won 1, Drew 2, Lost 6
FA Cup: Lost 2
League Cup: Lost 1
Leicester City (Dec 1995 - Jun 2000)
League: Won 1, Drew 3, Lost 4
League Cup: Won 1
Overall (22 games)
Won 3, Drawn 5, Lost 14