Sky sources are reporting that Chelsea have made a £20m bid to bring Benfica's Nemanja Matic back to Stamford Bridge.
The midfielder first joined Chelsea in 2009 but made just two appearances before leaving for Portugal in 2011.
He made that move to Benfica as part of the deal which saw David Luiz arrive at Stamford Bridge but Blues boss Jose Mourinho may now see Matic as the man to strengthen the centre of his midfield this January.
Matic has been capped nine times by Serbia and the 25-year-old has been a huge success since making the switch to Benfica.
The Portuguese side narrowly lost out to Porto in the race for the title last season and were beaten 2-1 by Chelsea in the Europa League final but Matic was named the Primeira Liga Player of the Year.
Some reports claim that he has a buy-out clause of around £37m in his current contract.