The Northern Irishman has defended the Gunners boss following his side's comfortable 2-0 FA Cup victory against them at the Stadium of Light on Saturday evening
The home side booked their place in the FA Cup quarter-finals with an impressive 2-0 triumph over the visitors, with Kieran Richardson opening the scoring before an own goal from Alex Oxlade-Chamberlain sealed the victory.
When asked if he believes Wenger's days as Arsenal boss are numbered, O'Neill said: “My view is that when he eventually decides to retire he will be considered by everyone, including me, as one of the great managers of the game.
"We might not always see eye to eye about events but I personally think he has been fantastic for the English game, so of course he will be disappointed at having lost the game but I don’t think the criticism that we all receive passes round, but I don’t think it is particularly merited. That is my view. He has been one of the great managers and will be considered so.”
The former Aston Villa boss also expressed his delight at making the last eight of the FA Cup after his side's two-goal triumph over the north London side.
“If anything we were getting stronger as the game went on,” O’Neill told reporters. “I am really pleased for everybody concerned with the club, particularly the players who were excellent today, not only in terms of working hard but also when we had the ball because we tried to use it.
“There was plenty of confidence and the self-belief is getting stronger which is great to see. They feel as if they can win matches.
“I am delighted to be in the last eight. Today you felt that the first goal was going to be of major importance. It would give that extra belief and we took that into the second half.
“We put a big effort into the game and that did not surprise me because we have been doing that for some particular time. I think I pleasantly get surprised by them if the truth be known.”