The Premier League side will meet the La Liga leaders across two legs at the end of April, and Ferreira, who made 214 appearances for Chelsea, believes that the Stamford Bridge outfit face a difficult task to overcome Diego Simeone's team.
The 35-year-old, who was representing Chelsea in Nyon, said: "I think it will be a difficult game, it will be a 50-50 chance of reaching the final for Chelsea.
"Atletico deserve to be there after beating Barcelona. But Chelsea have a wonderful team and a wonderful manager and they will try to do their best to reach the final."
The first leg in Madrid will take place on April 22, with the reverse fixture being staged in West London eight days later.