Southampton did their part to put the pressure firmly back on Tottenham to keep pace with Premier League leaders Chelsea.
Eden Hazard saw his early goal cancelled out by ex-Blues midfielder Oriol Romeu, but Gary Cahill and Diego Costa, who struck twice, added tallies in a 4-2 win for Chelsea at Stamford Bridge.
Despite a valiant first-half effort from the visitors, Chelsea moved within 12 points of the title with five games left.
Hazard’s opening goal — his 15th of the Premier League season — with five minutes gone was the product of Costa’s cutback following textbook build-up, which started from the hands of Thibaut Courtois.
Southampton managed to overcame their pedestrian start as Chelsea carved up their defence on several occasions, and they levelled proceedings after Steven Davis did well to earn a corner following a deflection.
Romeu would stab home on the rebound from the resulting set piece on 24 minutes after Manolo Gabbiadini had his initial shot saved at the near post.
Chelsea, looking to retake command, missed an opportunity on the break as N’Golo Kante weaved into the heart of the Southampton defence before his dinked cross required the attention of Jack Stephens.
In the mele, Costa had a penalty appeal waved off by Lee Mason after the forward appeared to have been knocked down from behind in the box.
The hosts were fortunate, however, to watch Sofiane Boufal hit the side netting after more sub-par defending from Southampton’s corner almost led to a surprise lead.
But Chelsea would go ahead on the stroke of half-time as Gary Cahill, who fought off the feet of his own teammate, netted for the fifth time this season with a thumping header.
Costa’s 50th Premier League goal made it 3-1 shortly after the restart, as he held off Ryan Bertrand before heading in Cesc Fabregas’ cross beyond a leaping Fraser Forster.
Southampton continued to trouble Chelsea from set-pieces, but Gabbiadini could only fire into the side netting on 69 minutes as they looked to pull one back.
A diving Forster kept out Kante 10 minutes from full-time, but Costa found a fourth Chelsea goal with a strike that had the keeper flat-footed.
Bertrand added a consolation goal for Southampton as he turned in a header on the full-time whistle.
Chelsea: Courtois, Azpilicueta, David Luiz, Cahill (c), Moses (Terry 86), Kante, Matic, Alonso, Fabregas (Pedro 77), Diego Costa, Hazard (Willian 90).
Unused subs: Begovic, Ake, Chalobah, Batshuayi.
Goals: Hazard (5), Cahill (45+1), Costa (54, 89).
Bookings: Kante (40), Fabregas (49).
Southampton: Forster, Bertrand, Yoshida, Stephens, Cedric, Romeu, Davis (c), Ward-Prowse (Long 82), Tadic, Boufal (Redmond 68), Gabbiadini (Rodriguez 86).
Unused subs: Hassen (GK), Caceres, Clasie, Hojbjerg.
Goals: Romeu (24), Bertrand (90+4).
Bookings: Romeu (60), Tadic (73).