The midfielder believes the decision reflects the trust and respect he has quickly earned from new head coach Xabi Alonso.
Chelsea’s summer tour visited Sydney, Hong Kong, Indonesia and Malaysia before ending on Sunday.
“I didn't expect to be captain at this age for this big club, so for me it's just a pleasure, and I enjoyed it a lot. For me it means everything, because I didn't expect it,” he told club media.
“I feel like it's a message for me and for all the players, that it's not about the age, but maybe about your maturity, so it's about learning and staying positive.
“I’m enjoying working with the manager.We mentioned it a lot in this pre-season, but he was a very good player.”
