Martin O'Neill and Arsène Wenger have not always seen eye to eye yet Sunderland's manager believes that some of the flak flying his Arsenal counterpart's way has been unwarranted.

"I'm not here to defend Arsène Wenger. He doesn't need defending by me, who isn't his favourite character," said O'Neill, no stranger to technical area contretemps with Wenger. "Very little surprises me in the game now but I am surprised at the criticism surrounding him. His influence on English football has been immense.

"If he left tomorrow morning he would be considered Arsenal's greatest manager – and there have been some excellent ones. Much has been made of the fact they haven't won a trophy for seven years but during that time they have qualified for the Champions League each season. They have also recently lost some quality players of the sort that are hard to replace immediately."

On Saturday evening Sunderland aim to further undermine Wenger by knocking Arsenal out of the FA Cup at the Stadium of Light. "We are capable of winning," O'Neill said. "We have one or two players who can definitely cause Arsenal problems."

Such difficulties may be exacerbated by the state of Sunderland's pitch, which O'Neill conceded is "disappointingly poor". Asked whether a heavy surface prone to cutting up may hinder Wenger's players, he smiled mischievously. "You are assuming that they are a better passing team than us," he said. "So I will let you get on and assume that."

As a former law student, O'Neill knows assumptions are dangerous things and he suspects that some erroneous ones are being made about Wenger.

"I noticed it the season before last when I was managing at Aston Villa," said O'Neill, who may recall Lee Cattermole in central midfield against Arsenal following his combative captain's recovery from a hamstring injury.

"I just think it's par for the course these days, people can make a statistic out of anything. It becomes your turn, then it flips around. Wenger made that point – if you win a couple of games it moves on to someone else for a while and comes back round again. While it remains like that you just have to live with it.

"It's symptomatic of the game today but not every single team can win the Premier League. That's not to say that managers of yesteryear weren't chased out though. Lets be fair, if you don't win enough games then you know that, eventually, you will be in trouble."