Ex-Chelsea midfielder Deco has tipped Jose Mourinho to bring confidence back to Manchester United's players.
Mourinho has been heavily linked with the manager's job at United since his sacking by Chelsea, with Louis van Gaal enduring a tough campaign in the Old Trafford hot seat.
The Dutchman is expected to either be forced out or walk away from United before the start of next season - despite his contract running until the summer of 2017.
And Deco, who won the Champions League with Porto under Mourinho in 2004, has backed his former manager to succeed with United if he is given the reins.
"I think he will change them a lot," Deco told Squawka. "United need to be back at a high level and Mourinho is the man to do that.
"He will bring their confidence again, for the players, for the fans, for the people. You cannot win something without it."
Despite their disappointing season, United manager Van Gaal is expected to remain in his position until summer after Mourinho admitted he wants to start afresh at the start of next campaign.
"I always feel that it's better to wait, not to rush, better to be calm, to wait for the right moment, the right move," Mourinho said. "I feel that starting the next season with a new club and project is probably the best thing for me.
"It's quite a funny career. I am the English champion, and I still have no job.
"I read so many different things. One day it says I go to China, another day it says I go to Italy, and people say I'm back to Inter Milan. I'm here – probably, you are saying I will to the Singapore national team.
"But the reality is I have no job, and at the moment I'm happy not to have a job."
