I come back [to Old Trafford] it would be as number one. I played under some great managers in my career including Platini, Beckenbauer and Guy Roux at Auxerre. But for me Sir Alex is the best. Guy Roux worked with me at the start of my career from the age of 15 to 22, so of course I learnt a lot from him. But as a mature player, Sir Alex was the one who taught me the most.