Marcus Williams has joined League Two outfit Scunthorpe United on-loan until 1st January 2014.
The 27-year-old rejoins the club where he started his professional career, having made 50 appearances for the Blades, after joining, initially on-loan, from Reading in September 2011.
The left-back signed a permanent deal at Bramall Lane in January 2012 and contributed to the Blades reaching the play-off final during the first season in League One.
His last game in United colours came in the 3-1 defeat at Brentford in August.
Williams could make his second Iron debut against Torquay United at the weekend.