Eden Hazard continued his sensational start to the season as unbeaten Chelsea inflicted more St Mary’s misery on Southampton.
The Premier League’s top-scorer coolly converted his seventh strike of the campaign with half an hour played to put the Blues on course for a deserved 3-0 success on the south coast.
Ross Barkley poked home to double the advantage following Willian’s second-half free-kick, before Hazard laid on a stoppage-time third for substitute Alvaro Morata.
Victory keeps Maurizio Sarri’s men among the pace-setters, while defeat for Southampton leaves them with just one home league win since last November.
Saints were second best for the majority of Sunday’s clash, although Danny Ings squandered an excellent opportunity to fire his side ahead and Nathan Redmond struck the crossbar late on.
Despite avoiding a competitive defeat since Italian Sarri replaced compatriot Antonio Conte during the summer, the Blues have wobbled slightly in recent weeks.
Wesley Hoedt and Olivier Giroud battle for the ball at St Mary’s (Andrew Matthews/PA)
They dropped two points in the London derby with West Ham a fortnight ago, conceded a late equaliser against title rivals Liverpool last weekend, and laboured past Hungarian champions Vidi on Thursday.
After making multiple changes for that Europa League clash, Sarri reverted back to the team held by Jurgen Klopp’s Reds, albeit replacing Mateo Kovacic with England midfielder Barkley.
Chelsea began in confident fashion and almost went ahead in fortuitous fashion when Willian’s shot deflected off Wesley Hoedt and looped on to the top of the bar.
Southampton’s home support has been starved of recent success, witnessing just four league wins from the previous 27 games at St Mary’s.
The hosts were pinned back for much of the first half, although Manolo Gabbiadini forced Chelsea’s £71.6million goalkeeper Kepa Arrizabalaga to get his gloves dirty with a curling effort from range.
Saints striker Ings, who has hit four goals since his summer switch from Liverpool, then somehow directed a close-range volley high over the bar following fine build-up play between Redmond and Ryan Bertrand.
Chelsea, unfamiliar in a light blue strip paired with fluorescent orange socks, were denied a penalty when Olivier Giroud went down under a challenge from Dutch defender Hoedt, before edging ahead minutes later.
Saints midfielder Pierre-Emile Hojbjerg was caught dawdling on the ball by the recalled Barkley and he slipped through Hazard to emphatically slot past Alex McCarthy.
The home side started the second period in the ascendancy but were again wasteful in front of goal.
Unmarked former Chelsea defender Bertrand volleyed over at the back post from Hojbjerg’s cross, while Ings directed an effort straight at Kepa.
The visitors took advantage of the profligacy, doubling the advantage with 57 minutes played after Hazard was tripped by Ings.
Willian delivered the resultant free-kick deep into the area and Giroud – on his 200th Premier League appearance – acrobatically fired across goal for Barkley to tap in his first goal for the west London club.
Saints winger Redmond threatened to set up a nervy finish when he rattled the woodwork, while Blues striker Morata would have added a third but for a smart stop from McCarthy.
The Spaniard was not to be denied a goal though and coolly lifted Hazard’s pass over McCarthy in stoppage time following a prolonged period of possession to seal his side’s sixth league victory of the season.