Some were surprised that Jose Mourinho did not make even more changes to his side for the visit of Championship opposition in the cup, but a dismal first-half showing threatened a bigger fitness problem – a replay.
However replacing Oscar and Andre Schurrle with Diego Costa and Willian did the trick, as the two half-time subs formed a lethal four-man whirl attack with Didier Drogba and Loic Remy.
Willian’s unstoppable right-footed drive finally broke the deadlock just shy of the hour before Remy added a goal to his assist for the opener with the second 20 minutes from time, putting in the rebound after Costa’s shot was blocked.
The impressive Kurt Zouma excellently headed home from a corner to seal progression at the first attempt for the home side two minutes after they had doubled their lead.