The game at Stamford Bridge will therefore be played on Sunday, 30th January with a 4pm kick-off time.
The BBC, who have the rights to show three live Cup games at the 4th round stage, will be screening Southampton v Portsmouth at 12.30pm on Saturday, 29th January and Manchester Utd or Exeter v Middlesbrough at 5.20pm on the same day.
On Sunday, 30th January the tie between Oldham and Bolton will be screened live by the BBC at 1.45pm.
Note: As a result of the Cup tie being played on the Sunday, Blues' home Premier League game against Southampton on Tuesday 1st, February has been put back a day and will now be played on Wednesday, 2nd February with a 7.45pm kick-off time.