Chelsea are facing a potential fixture pile up if they come through their Europa League match with Steaua Bucharest on Thursday.
Rafa Benitez's side cannot rearrange their FA Cup replay against Manchester United for next week because of the international break. That means the tie is likely to be as late as April. If it is played on the weekend of 6 April, the Premier League would have to cancel Chelsea v Sunderland on Saturday, and Manchester United v Manchester City on the Monday.
Chelsea meet Southampton on Sunday 31 March and could then play the quarter-final of the Europa League on Thursday 4 April, followed by the FA Cup replay with Manchester United two or three days later. The semi-finals of the FA Cup are due for 13 and 14 April.