Third-placed Chelsea suffered a shock 4-1 defeat at the hands of Brentford last week before losing 3-1 against Real Madrid in the first leg of their Champions League quarter-final.
But they restored confidence on Saturday by putting Southampton to the sword, racing into a 4-0 lead with just half an hour played.
Goals from Marcos Alonso, Mason Mount, Timo Werner and Kai Havertz put the game beyond the home side's reach by half-time.
Werner and Mount both scored again early in the second half as the match became an embarrassing rout.
