Sky Sports sources understand Bolton defender Gary Cahill travelled to the capital on Friday evening to conclude his Chelsea move.
Bolton agreed a fee with the Blues for the England international before this month's transfer window opened but negotiations have run on throughout the beginning of January.
It appears Cahill has finally reached a deal with the Londoners, with reports suggesting it will keep him at Stamford Bridge until 2017.
The centre-back is thought to have travelled to Chelsea on Friday night to undergo a medical, with the deal expected to be confirmed by the end of the weekend.
Should Cahill complete the move, it would mean Premier League strugglers the Trotters will be without their star man for Saturday's trip to Manchester United.
Owen Coyle is thought to be closing on USA international Tim Ream as a replacement for Cahill, with the New York Red Bulls man thought to have been at the Trotters' training ground on Friday.