Sky Sports sources understand QPR are in talks with Sunderland over a possible deal for Anton Ferdinand.
Rangers have already signed Joey Barton, Luke Young and Armand Troare since Tony Fernandes assumed control of the club.
Neil Warnock had stated he would like to bring in four or five players before the close of the transfer window and it now looks like that could be the case.
Ferdinand fell out of favour with Steve Bruce last season but has been partnered with Wes Brown in defence at the start of the new campaign.
The 26-year-old is in the final year of his contract and there have been no attempts to open discussions about a new deal.
Titus Bramble and Michael Turner are both edging closer to full fitness, while John O'Shea has recovered from a hamstring injury.
Their return to fitness means Bruce can allow the player to leave, which would free up funds as he tries to sign a striker.
Ferdinand, who is the younger brother of England and Manchester United defender, Rio cost the club around £8million three years ago.
But it is thought they will now be prepared to take as little as £1million for the former England Under-21 international.