Marcos Alonso opened the scoring for the visitors. The Spaniard tucked one away following a cheeky lay-off by Mason Mount to set him up in the eighth minute of the game. Mount soon doubled his side's advantage with a stunning low-lying shot from outside the box.
Timo Werner made it three for the visitors in the 21st minute. The Germany international pounced on a misplaced pass by James Ward-Prowse and went around Fraser Forster to score one. Kai Havertz scored an easy tap-in minutes later. Werner's shot hit the post and fell kindly for Havertz in front of goal.
Chelsea continued their onslaught even after the restart. The Blues scored their fifth through Werner as he smartly slotted one in after Forster made a great save to deny N'Golo Kante. Mount capped off a beautiful game as he scored the sixth goal in the 54th minute.
On that note, here's a look at five talking points from the game:
#5 An eye on the Real Madrid fixture
Thomas Tuchel decided to rest some of his key players following an impressive first-half performance. The German substituted Mount, Havertz and Thiago Silva at various stages in the second half. It would certainly be to rest them ahead of the crucial return leg of the UEFA Champions League quarter-final against Real Madrid.
Havertz was one of Chelsea's most effective players against Los Blancos in the first leg as they lost 3-1. The Blues will need him to be at his best when they visit the Santiago Bernabeu. These three could be the key to overturning the tie around and Tuchel knows it perfectly.
#4 Southampton could have conceded a lot more
It may sound astonishing but the hosts could have conceded more than they already did. They have one man to thank and it is Fraser Forster. Had it not been for him, they could have ended up with nine goals in the back of the net. Forster made eight saves throughout the game against Chelsea and some of them were definitely heading in.
Forster did a great job keeping in mind how the Southampton defenders set themselves up throughout the game. The hosts played a high back-line even after going four goals down. The 34-year-old saved his side from further embarrassment.
#3 Chelsea are on an impressive away games run
Chelsea equalled their record of seven successive away wins in all competitions following their emphatic win over Southampton. The last away game the Blues failed to win in an away game was against Brighton and Hove Albion on January 19. This shows how impressive they have been away from home
The Blues will be hoping to continue their streak when they play Los Blancos next week away from home in Madrid. It is imperative that they put their best foot forward at the Santiago Bernabeu if they are to advance any further in the UEFA Champions League.
#2 Massive performances by Mason Mount and Timo Werner
Mason Mount scored two goals and assisted one. The Englishman was on fire upfront. He won five duels, made eight recoveries, won three tackles and created one chance throughout his stay on the pitch. He wrecked havoc every time he moved closer to the box.
Timo Werner was fantastic against Southampton as well. He was absolutely lethal. The German international scored two goals and rattled the woodwork thrice in eight shots. Werner could have had a flurry of goals to his name had he been a bit luckier.
#1 Chelsea respond in style
Following a humiliating loss at the hands of Real Madrid in the midweek UEFA Champions League fixture, the Blues have responded in some fashion. They rattled the hosts as they smacked six goals past them. They overcame the mistakes that they made over the past week and put on a massive show. Chelsea were flawless offensively as well as defensively.
The visitors looked hungry and were out to prove a point as they were ruthless and showed no mercy. They were perfect against Southampton and will be hoping they can replicate the same against the Spanish giants in the upcoming fixture.