In an open letter posted on his Twitter page, he wrote:
“To my Chelsea family,
“After ten years, 374 appearances and eleven trophies, it is time to say goodbye.
“Where do I begin? I joined Chelsea as a 19-year-old kid from the Norwegian Premier League, making my debut in the Community Shield. I say goodbye as a champion of England, a champion of Europe, and proud captain of my national team.
“To play in the Premier League, the best league in the world, is every professional player’s ambition. But to play for Chelsea, to become part of the Chelsea family, to work with some of the best managers and players in the world, has truly been an honour.
“Every achievement I have been part of in my time at Chelsea holds a special memory: my first goal, against Macclesfield in 2007 (even though there were only five more after that!). The nail-biting end of the 2010 season – securing the title on the last day, scoring a record 103 goals in the process, and winning the FA Cup a week later. Didier’s extra time winner against Manchester United in the 2007 FA Cup Final. Beating two of our biggest London rivals in League Cup finals. Winning the Europa League in Amsterdam, with one of the last kicks of the game.

Nice move