Manchester United legend Rio Ferdinand believes that between 2006 and 2010, he was the best defender in the world.
Ferdinand spent 12 years at Old Trafford, and won a number of honours, including six Premier League titles and the Champions League.
And, the former England captain believes that at his peak, he had no rivals in his position.
"I looked around my dressing room and saw great centre halves and thought 'I'm going to out-work you, do more than you, be better than you," Ferdinand told BT Sport.
"I took it as an embarrassment to myself if I wasn't playing as well as that centre half.
"Even in a game where you're playing against big players. John Terry at Chelsea, Sol Campbell at Arsenal… You're looking across the pitch thinking 'right, I've got to play better than them.
Asked by BT Sport if he thought he was the world's best defender, Ferdinand replied: "Yeah, yeah I did."