Norwich City and Fulham drew 1-1 at Carrow Road in their 3rd Round clash at Carrow Road, forcing a replay whiklst Sheffield United recorded the result of the round with a 2-1 win at Aston Villa - both on 4th Janaury.
Having earned that victory the Blades discover less than 24 hours later that they would host the winners between Premiership duo Fulham and Norwich City.
The pair will play their replay tonight at Craven Cottege and the winner will travel to Bramall Lane on Sunday, 26 Janaury (13:00 Kick-Off) live on BT Sport.
Under competition rules, should tonight's game be all square at 90 minutes then 30 minutes extra-time will commence. Should there still be no winner decided then a penalty shoot-out will follow.
The game tonight will kick-off at 7:45pm and will also be shown live on BT Sport for those who wish to see the action unfold.