Barcelona vice-president Carles Vilarrubi believes that Jose Mourinho will create a "disaster" at Chelsea if he returns to Stamford Bridge this summer.
The Portuguese coach is reported to have agreed a four-year contract with the West London outfit following Real Madrid's announcement that Mourinho will leave his managerial post at the end of the Spanish season.
"It is not good for English football," The Telegraph quotes Vilarrubi as saying. "Chelsea maybe think they had a good time from him in the past, but you will see the real Mourinho now.
"If he behaves like he did in Spain it will only be an unhappy relationship. A disaster. And at his age he is not going to change.
"My position is not because he was the coach of a rival, but because of who he is and what he did. His three years in Spain he only creates disagreements, arguments. There is nothing positive he brings."
Mourinho left Chelsea in 2007 for Inter Milan due to a reported feud with Blues owner Roman Abramovich.