Mata arrived at the club after Mourinho's departure but is well aware of everything the Portuguese has achieved and would be happy to see him handed the reins.
"Jose is one of the best," Mata said. "He won everything in every country he was - in Portugal, in Italy, in London with Chelsea, and in Spain as well.
"We don't know really what is going to happen but if he comes he is welcome because he is one of the best and Chelsea always want to be a top side.
"If he comes we are going to be happy to have him."