Sunderland boss Martin O'Neill has questioned whether Arsenal can recover from the sale of Robin van Persie.

He admitted his players found it much easier to keep a clean sheet in the 0-0 between the sides on Saturday after the Gunners sold Van Persie to Manchester United.

O'Neill said: "It's a major loss to them, anyone would suffer if they lost a world-class player like that. Real Madrid would if they lost Cristiano Ronaldo, Barcelona would if they lost Messi - he was every bit as important to Arsenal.

"It's a major, major loss for them. He was the fans' favourite here. Before I came up to Sunderland, I went to a game at the Emirates and not only was he brilliant but the crowd were right behind him.

"You think you've got ­everything, you're playing for Arsenal and then you decide that is it. What more can a manager do? You've got an unhappy player here for a year and he plays under duress or do you decide to take the money?"