Cahill, 21 was signed by Blades boss Bryan Robson in September 2007, making his debut at Selhurst Park in the 3-2 defeat to the hands of Crystal Palace.
Along with on-loan Manchester United defender Phil Bardsley (right full-back), he and Cahill have struck up a great partnership in the United back four which turned a depleted team which failed to pick up points into a potential promotion chasing outfit.
The Dronfield born centre-half was a mastermind in the Blades successful five match winning streak away from home; picking up thirteen points at; Leicester City (1-0), Hull City (1-1), Stoke City (1-0), Charlton Athletic (3-0) and Coventry City (1-0). He also netted in back-to-back wins at the Britannia Stadium and the Valley.
As well as his match winning performances the former England U-21 international was also voted as 'Blades-Mad Player of the Month' for November 2007 by members of this website (www.blades-mad.co.uk).
He played his final game for United last Saturday in the big South Yorkshire derby victory against Barnsley (1-0) at Bramall Lane and returns to the Birmingham based club after making 16 league appearances and netting two goals.
It is not sure if Cahill will join the Blades once the January transfer window hopes, but its safe to say that he would be a huge benefactor in Bryan Robson's bid to win promotion to the Premier League with Sheffield United if his move became permanent.