The Chelsea manager wants to sign a new central defender for the Premier League side.
Terry's future under threat by the tactics of Villas-Boas
Andre Villas-Boas has asked for defensive reinforcement in January as he seeks to restructure a Chelsea squad that has struggled to implement his tactics. The Portuguese coach is eager to add a centre-back comfortable playing a high offside line and implementing his Barcelona-inspired approach to football.
With potential signings including Gary Cahill, the Bolton Wanderers' England international, the Chelsea manager is confident that he retains owner Roman Abramovich's full backing despite heavy Premier League defeats at the hands of Manchester United and Arsenal in his first months at the club.
Instructing his defenders to play far further from goal than they were accustomed to under Carlo Ancelotti and other predecessors, Villas-Boas's team has conceded 15 goals in his first 11 Premier League fixtures - keeping just two clean sheets.
Selection in central defence has been erratic, and John Terry has been stripped of his status as an automatic starter.
His diminished pace and agility have been exposed by tactical instructions that place him far from the relative safety of defending the edge of his area. That has done little to help Terry, 30, at a time when his captaincy of England and Chelsea is threatened by an investigation into alleged racial abuse.
While Villas-Boas considers him the most consistent of his four senior centre backs, Branislav Ivanovic also has problems with playing the high line fundamental to Chelsea's new approach.
Alex's history of injury problems prevent the Brazilian playing regularly. The fourth central defender, David Luiz, is athletically and technically best-suited to the Villas-Boas approach, he has yet to rectify a tendency to make errors of judgement.
The manager's concerns are long-standing, with efforts made to rejuvenate the defence in the summer window. Scott Dann was considered before he swapped relegated Birmingham City for Blackburn Rovers, and there was an unsuccessful approach made for the Manchester United-bound Phil Jones.
With some senior players discontented by aspects of Villas-Boas's management, the request for further investment in new players will test the strength of Abramovich's support for a coach who was the second-choice behind Guus Hiddink for the post, before his June appointment.
The Russian billionaire, however, is understood to have been convinced by arguments that Chelsea's squad requires further rejuvenation if it is to successfully adopt the football of the Barcelona side he so greatly admires, and that Villas-Boas remains the right man to lead that process.