Deco’s two year stint in the Premier League was tinged with highs and lows.
He showed his class on numerous occasions - Chelsea fans will never forget his 30-yard stunner on his debut - while also helping the Blues win a Premier League and FA Cup double in the 2009-10 season.
Yet injuries affected his second season at the club and he would leave for Fluminense after two years at Stamford Bridge.
Deco played under Luiz Felipe Scolari and Carlo Ancelotti - he arrived after Jose Mourinho was sacked and left before the Portuguese manage returned.
So to see him back Mourinho’s team for the Premier League title, not the Blues, will come as a surprise to many Chelsea supporters.
They’ll do well to remember, however, that Deco played under Mourinho at Porto. Clearly, their Champions League win in 2004 has forged a stern loyalty on Deco’s behalf.
"When Jose is at a club, everyone is looking at him," Deco said, per Goal. "I think he is the right man for the job.
"United need to bring back the pride of the club and bring back the victories and titles. Jose Mourinho is the man to do that.
"The Premier League is tough. A lot of new players need to know each other, it's complicated. They will improve and fight for the Premier League for sure.
"The expectations are so high and they invested a lot. Everyone is waiting for something good from United. From my perspective I hope Jose can win the Premier League with United like he did with Chelsea.
"Different players and a different club. You don't change everything, you need to adapt in a new club. This is normal."
Conte will bring new ideas
Chelsea replaced Mourinho with Antonio Conte in the summer and Deco believes the Italian is a good fit at the west London club.
The former Barcelona man continued: “It’s normally difficult for all the clubs when you change managers. He is a very good coach, he won everything at Juventus.
“He will bring new ideas but I think the Premier League is more difficult than before. The level has improved a lot. It is very hard to win games. I think it is normal.
“They have got Conte to bring the club to a high level again. They will try to win the Premier League and qualify for the Champions League but of course Chelsea need to fight for the title every year.”