The former Porto man, linking up with Luiz Felipe Scolari, mentioned to the Press Association that the Blues had to be highly-regarded.
He said, "It is hard to compare two different teams, both Barcelona and Chelsea have very good players, but Chelsea have the edge and have a great team spirit.
"I am very glad to join Chelsea and I am happy after being able to link up with Mr Scolari again and together I hope we can do very good things for Chelsea."
The Blues kicked off their pre-season with a 4-0 win over Guangzhou Pharmaceutical on Wednesday - a match in which Deco's performance drew praise.
"We played very well on Wednesday considering it was our first game, but we did not play that well and we hope to play better on Saturday after being able to train together more," he said after appearing for an hour in China.
"I still have a lot of things to learn, coming to Chelsea is a new challenge for me. We have a strong team and I can learn a lot from them despite being 30."
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