Aston Villa boss Martin O'Neill believes Sir Alex Ferguson's record over more than two decades at Manchester United will "stand the test of time".
O'Neill will be hoping Villa can win at Old Trafford for the first time in 26 years in Saturday evening's Barclays Premier League clash. But, whatever the outcome, the former Celtic manager knows Ferguson's achievements with the Red Devils are unlikely to be surpassed.
"Sir Alex is at the top of the tree. He has been a brilliant manager for a long, long time and proved himself every year for 20-odd years," said O'Neill. "Anyone who has been at a club of that standing for that length of time, and been as successful as he is, is fantastic. It just couldn't be repeated."
He added: "Carlo Ancelotti mentioned he was at (AC) Milan for eight years and, in Italian terms, that really is a lifetime.
"For someone to be at a club the size of Manchester United year in year out, and be as successful, is phenomenal.
"He has built not just teams, but successful teams. Eventually you have to change teams if you are there for that amount of time. There is a certain lifespan and then you go onto develop another side.
"What has been so fantastic is Sir Alex has developed these teams and they have all been successful.
"He is now contesting Champions League finals on a more regular basis and winning championships. The record is there for everyone to see and will stand the test of time."
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