Villas-Boas left Porto last summer after winning the league, cup and Europa League, but he has found life in charge of Chelsea distinctly more difficult, and currently has the worst record of any of the club's managers since the arrival of owner Roman Abramovich in 2003.
A number of Chelsea players have seemingly lost faith in Villas-Boas, with sources leaking stories to the press and Nicolas Anelka and Alex both exiled ahead of their departures in January, while it is reported that members of the squad spoke out against Villas-Boas when Abramovich held a meeting in the wake of the 2-0 defeat to Everton.
Pinto da Costa, who employed both Mourinho and Villas-Boas at the Estadio do Dragao, believes the latter will ultimately prove a success in West London but feels the former is still wielding too much influence over the squad.
Pinto da Costa told La Gazzetta dello Sport: "He will be successful with Chelsea because his contract isn't just for one year. He needs time to mould his own team and he can't do that as long as there are players, as I've heard, who exchange text messages with Mourinho - and Abramovich knows this."
Meanwhile, Guus Hiddink's agent has refused to be drawn on speculation he could return to Chelsea should Abramovich lose patience with Villas-Boas.
Cees van Nieuwenhuizen said: "I know they are not doing too well at the moment, but Guus never puts himself in a position that he says he is interested in whatever job if there is still coach who is doing the job. For him, that's not the way to treat your colleagues."
He added: "He has offers on the table, obviously, but he is not in a hurry and he is making up his mind."