Benfica are ready to open negotiations with a number of clubs with a view to selling star midfielder Nemanja Matic, reports Portuguese source O Jogo.
Both Chelsea and Manchester United have been credited with a strong interest in the player with Jose Mourinho quoted by the same source last week praising the player's development since leaving Stamford Bridge in 2011.
The Serbian international signed for Chelsea from MFK Kosice in 2009, but only made two first team appearances before being sold to the Portuguese club as part of the deal that saw David Luiz move the other way.
His development in Portugal has convinced Mourinho on his ability and, despite admitting it will be tough to coax Matic away from Benfica in January, could be boosted by news that Benfica are willing to sell him after the crunch tie with Porto on 12th January.
But the Blues will face competition from Manchester United with David Moyes desperate to strengthen his squad in an attempt to resurrect a terrible start to his managerial reign at Old Trafford.
Both Michael Carrick and Marouane Fellaini have struggled for form and fitness so far this season, leaving Moyes hunting for midfield reinforcements this month.
Benfica are reported to have placed a £20m price tag on Matic's head but are willing to negotiate a deal to ease financial pressure on the club.
O Jogo is reporting that Benfica have already sent scouts to find a replacement for Matic, suggesting they are preparing for the imminent loss of their star player.