He said: "I knew some had doubts about me coming to the club, but they probably love me now.
"There was never a flicker of doubt in my mind about coming because it was Sunderland. I jumped at the chance.
"When someone like Roy Keane comes in for you, a man of his calibre and someone who has achieved what he has in the game, it means a lot.
"It was a big opportunity to show people I can play in the Premier League."