Porto president Pinto Da Costa has claimed beleaguered Chelsea manager Andre Villas-Boas' work is being disrupted due to the sustained contact of key players with former manager Jose Mourinho.

He believes Villas-Boas' authority is being destabilized by Mourinho's communication with his former players.

"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," The Telegraph quoted Da Costa, as saying.