The 35-year-old has enjoyed a glittering career at Stamford Bridge, collecting 11 major honours - including three Premier League titles and one Champions League - but announced on Monday that he will leave.
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"It was very difficult," the midfielder told reporters of his decision in the build-up to England's pre-World Cup friendly against Ecuador.
"After 13 years, the club was part of my life. It is difficult but you have to move on, the club will move on. I'll probably address it more to the Chelsea fans at a better time.
"I am here to concentrate on England. It was almost a relief to say it so I can move forward.
"I am really happy to be among an exciting England squad, full of skill, speed and exuberance."