The 24-year-old Cork born midfielder arrived at Manchester United from Celtic in the summer of 2004, but was allegedly amongst the player's criticised this week by Old Trafford captain Roy Keane.
A move to Sunderland failed to materialise this summer, yet he will now have the chance of regular first team action after signing a loan deal with the Whites until January. He trained with the first team squad this morning and could make his debut against Preston tomorrow at Elland Road.
"I felt it was right to bring someone in because we need to make sure we are covered in midfield over these next few months," Kevin Blackwell said. "We have a few players one card away from a suspension and if I lose one of them then my options are limited. Bringing Liam in allows us to cover midfield and also to freshen things up."