Diego Costa’s goal drought ended with a brace at Stamford Bridge as Chelsea tightened their grip on the title with a 4-2 win over Southampton.

Former Blues midfielder Oriol Romeu had cancelled out Eden Hazard’s early opener but fit-again Gary Cahill restored the Londoners lead just before the break.  Costa then netted twice to end a seven-game drought in style, the first his 50th in England’s top flight.

Ryan Bertrand headed an injury-time consolation for a Southampton side that fought gamely but a victory that feels pivotal sees Antonio Conte’s team stretch their lead at the top to seven points.

Chelsea FC celebrating

Nearest rivals Tottenham can cut the gap back to four by beating Crystal Palace on Wednesday but after their FA Cup semi-final win over Mauricio Pochettino’s challengers at the weekend, the Blues landed another psychological blow with just five games left.

Conte had restored Hazard and Costa to his line-up after leaving them out for the majority of the game at Wembley, but a Blues backline bolstered by Cahill following illness had an early scare when David Luiz and Cesar Azpilicueta dithered with Manolo Gabbiadini lurking.

A smart set-piece saw Dusan Tadic loop a ball to Jack Stephens at the far post, his volley too tame to trouble, but Chelsea responded with a sweeping attack, Costa delaying his cut-back so Hazard could swing without breaking stride to find the bottom corner.

Hazard Goal

Southampton responded, Tadic and Cedric Soares involved in a one-touch move that Sofiane Boufal might have finished, but the hosts broke at ominous pace and Hazard came close to a second, leaning back when Costa deftly flicked into his path as Conte howled into his hands on the touchline.

Steven Davis saw a long-range effort deflected wide but the visitors drew level from the subsequent corner when Azpilicueta nodded backwards and Gabbiadini centred from an angle, Thibaut Courtois parrying only as far as Romeu as Chelsea’s Premier League run without a clean sheet stretched to 11 games.

The home fans roared on the team, as Chelsea upped the tempo, N’Golo Kante seizing the moment with a driving run from wide right to byline, before Costa fell in the box under the legitimate attention of Davis and Nemanja Matic – urged on after his weekend thunderbolt – lashed off-target.

Gary Cahill Goal

Boufal smashed into side-netting as the Saints’ set-piece armoury continued to cause bother but Chelsea finished the half strongly and made it count when Marcos Alonso headed Kante’s floated delivery back across goal and Cahill rose, applying a rudimentary finish as Costa shaped for an overhead kick.

Southampton snapped into tackles after half-time encouragement but Chelsea settled any jitters just minutes after the break when Cesc Fabregas showed for a short corner then scooped a ball with his laces that Costa muscled his way to meet, stooping to plant past Fraser Forster.

Diego Costa Goal

Claude Puel threw on Nathan Redmond in a bid to wrestle back momentum and Conte booted the bench as another corner carried danger, Gabbiadini blasting into the netting after a controlling touch made the angle too tight.

Fabregas, whose weighted pass for Costa had set up the opener, made way to hearty applause and though a late comeback never looked likely, Davis drilled a loose ball goalwards that, with Courtois committed, needed an intervention.

Chelsea-Celebrations

Chelsea tore forward as space opened up, Kante’s chip palmed away by Forster, but the job here was done and satisfied home hordes took further delight in a late cameo for departing John Terry.

Costa sealed a convincing win a minute from time, sparking a stylish move with a give-and-go on the edge of the box before slotting low into the corner, and though there was still time for more action, Bertrand’s injury-time header was a mere blot as Conte’s men edge closer.