The Blades made a successful passage into round two following a 3-1 win over Chesterfield at Bramall Lane with Jonathan Stead scoring twice and Danny Webber finishing off the rout, former Blade Jack Lester had leveled for the visitors.
United will play the MK Dons who are managed by former England legend Paul Ince.
The fixture is to be played week commencing Monday, 27 August 2007.