The former Sunderland centre-half, 26, has since fallen out of favour under new boss Darren Ferguson and is someway down the Scot's pecking order.
Leeds have stuttered of late and a 2-0 defeat to promotion rivals Millwall on Monday night was exacerbated by an injury sustained to influential stopper Patrick Kisnorbo.
The Australia international has suffered a serious Achilles injury and with his season over, a place on the plane to South Africa looks increasingly unlikely.
Simon Grayson has moved quickly to plug the gap and has agreed terms with Collins to stay at Elland Road until the campaign's conclusion.
Skysports.com understands a deal could be done by the end of Tuesday, with Collins due for a medical later in the afternoon.