Chelsea manager Andre Villas-Boas has described Bolton Wanderers defender Gary Cahill as an "interesting player".
The England international, who is out of contract in the summer, has been the subject of a reported £7m bid from the Blues.
Villas-Boas refused to comment on whether an offer had been made but did admit that the club are monitoring Cahill's situation.
"We are aware of Gary's contractual situation," Villas-Boas told a press conference. "He's an interesting player for the club."
Chelsea are believed to be looking to sign a centre-back during the January transfer window, particularly with the anticipated departure of Alex.
"You know that we have taken a decision this season regarding the central defenders, regarding Alex," added the boss.
"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."
Cahill, 26, joined Wanderers in 2008 from Aston Villa.
