Andre Villas-Boas has confirmed Chelsea are trying to close a deal for Gary Cahill, but insists the Bolton Wanderers defender is not his only target.
Following Alex's decision to submit a transfer request earlier this month, Villas-Boas is hoping to bring in a new centre-half in January to compensate for the Brazilian's expected departure.
The Chelsea boss confirmed his interest in Cahill last week, while Bolton revealed that the two clubs had engaged in dialogue regarding a possible deal.
Cahill is out of contract at the end of the season and the Trotters are ready to accept a fee in January rather than risk losing the England international for nothing.
Villas-Boas is keen to wrap up the signing of a new defender and doubts the Blues will seek to improve other areas of the squad when the transfer window reopens.
"Regarding what we are trying to do in central defence, we are trying to close a deal [for Gary Cahill] but I don't think we will do much more than that, maybe one more player," Villas-Boas told the club's official website.
"Central defence is our number one priority and we will try to solve it as soon as possible. We had initial talks with Bolton but that doesn't mean he is our only target."
Meanwhile, Villas-Boas offered an update on the fitness of Branislav Ivanovic and John Obi Mikel, who missed the Boxing Day draw with Fulham after picking up injuries in last week's stalemate with Tottenham Hotspur.
He added: "Branislav Ivanovic will be back sooner than Mikel.
"We are looking at the Portsmouth game for Ivanovic and it is not impossible for Mikel either but it might be a bit too soon."