He told the Sportske Novosti newspaper "I've decided in agreement with Middlesbrough bosses to break my contract with the club. After having reflected long and hard I will bring my professional career to an end."
The feeling on Teesside will be somewhat mixed, because on his day he was one of the most skillful players in the Premiership, but there are those who would question his committment and enthusiasm for the game.
I for one would question his record with injuries and desire to play for certain managers, perhaps it is time to let the young guys take over. However I do believe he did a great job for Boro in his first season here and would wish him well in his future career, whatever that might be.