Chelsea manager Andre Villas-Boas has labelled Bolton's England international defender Gary Cahill an 'interesting' player.
Cahill is one of Bolton's star performers and speculation over his future has been intense with his contract due to expire in the summer.
Bolton can ill-afford to lose the stopper, who turns 26 on Monday, on a free transfer, while their fight against the drop will suffer if he leaves next month.
Cahill impressed in Tuesday's six-pointer against Blackburn Rovers at Ewood Park, a 2-1 win that lifted Wanderers from the foot of the Premier League table.
It has been suggested Chelsea have tabled a £7million offer for Cahill, with Villas-Boas remarking the west Londoners are aware of the length on his contract.
"We are aware of Gary's contractual situation," stated Villas-Boas. "He's an interesting player for the club."
Chelsea are looking for cover in central defence with Brazilian Alex expected to move on in the New Year after submitting a transfer request.
He added: "You know that we have taken a decision this season regarding the central defenders, regarding Alex.
"We haven't decided yet what we are going to do with the Alex situation. We have to make the wisest decision, be it Alex, be it Cahill."