O’Neill’s Sunderland face Arsenal in the FA Cup today, with the London side’s boss Wenger under pressure again after a 4-0 loss to AC Milan in the Champions League.
“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.”