Deco has warned his Chelsea team-mates they face mission impossible trying to stop old Barcelona pal Leo Messi.
Deco spent four seasons at Barca before moving to London - and he has watched Messi's rise from the Catalan giants' reserves to the summit of world football. Guus Hiddink's Blues must now overcome Barca to reach the Champions League Final.
And Portuguese playmaker Deco said: "Leo Messi is incredible. He is one of my best friends and at the moment, almost impossible to stop on his day. He is an incredible player and, if he is on form, we can only wait and see who has the ability to stop him."
Chelsea are without Ashley Cole for the first leg of the tie, but Deco remains confident that last season's finalists can stop the free-scoring Spaniards.
He added: "Barca are one of the rivals we managed to avoid in the first knock-out rounds, but at this stage you cannot choose your opponents. "If we want to go all the way to the final in Rome we must beat them, which will not be easy. But we can do this.
"I still have a great deal of affection for Barca. I was very happy there and I cannot help but think fondly about that stage of my life."
Hiddink last night revealed Chelsea hired him as a panic measure because they feared they were "slipping" out of the Champions League.
The Dutchman took charge at Chelsea two months ago after Luiz Felipe Scolari was sacked after a poor run which saw them in danger of losing their top-four status.
i hope not.
