Match ends, Chelsea 4, Southampton 2.
Chelsea restored their lead at the top of the Premier League to seven points with a convincing win over Southampton at Stamford Bridge.
Antonio Conte's side had seen their advantage cut by Tottenham after the Blues' loss at Manchester United - but this was an emphatic response to follow on from Saturday's FA Cup semi-final win against their London rivals.
Eden Hazard and Diego Costa were both back in the starting line-up after Wembley and were key figures, the Belgian putting Chelsea ahead with a low shot after five minutes.
Former Chelsea midfielder Oriol Romeu bundled in an equaliser for Saints before Gary Cahill headed the title pace-setters back in front right on half-time, a moment that effectively decided the destination of the points.
Costa confirmed Chelsea's supremacy with a header early in the second half before scoring his second with a low shot late on.
Ryan Bertrand, another former Chelsea man, was on target in the dying seconds - but the victory was secured for Conte's men and now Spurs must respond at in-form Crystal Palace on Wednesday (20:00 BST kick-off).
Conte gets Hazard and Costa calls spot on
Conte manoeuvred his resources to perfection in the victory against Spurs at Wembley - and did it again here as Hazard and Costa made decisive contributions to a vital Chelsea win.
Conte raised eyebrows when he left his two most dangerous attackers out of his starting line-up on Saturday but used them as game-changers to great effect, deploying them as substitutes after an hour and Hazard then scoring the goal that swung the match in favour of his side.
Hazard and Costa were back from the start against Southampton and illustrated why they have been such integral components of Chelsea's rise to the top of the table this season.
The pair combined in the fifth minute for Hazard to score and Spain striker Costa was simply too strong for Bertrand when he arrived on the end of Cesc Fabregas' cross to score the third goal early in the second half.
And they were at it again soon afterwards - a neat exchange with Pedro leading to Costa getting his second and Chelsea's fourth with a powerful low drive in the closing moments.
Conte has put the Blues right back on track after their loss at Manchester United with wins in the FA Cup semi-final and here at Stamford Bridge - and his shrewd use of two of his most vital assets has helped him achieve it with a superb piece of management.
Chelsea survive test of nerve
Southampton - and of course Tottenham - would have been hoping anxiety and pressure might just have played a part in a shock result at Stamford Bridge.
And for a spell those factors came into play as the Saints recovered from Chelsea's perfect start to equalise through Romeu and then exert a measure of control.
However, the hosts kept their nerve to run out comfortable winners and avoid the sort of slip-up that would have played into the hands of Spurs.
Stamford Bridge ended the game in celebratory mood and the feeling that Chelsea's equilibrium had been restored after those recent slips at home to Crystal Palace and away to Manchester United.
Can Tottenham respond?
"We've put pressure on Spurs," said goalscorer Hazard.
Mauricio Pochettino's side will have felt the door had opened when Chelsea lost at Old Trafford and the gap at the top of the table was reduced to only four points. Suddenly the pressure was on Conte and his players.
The tables have now been turned and it will be Spurs and their manager who will be feeling the heat and the need to win when they travel to in-form Crystal Palace on Wednesday.
Spurs have reeled off seven straight league wins - their best sequence since 1967 - but all the self-belief built up during that run will be required to face Sam Allardyce's rejuvenated side, who have beaten Chelsea, Arsenal and Liverpool in recent weeks.
They will not only have to respond to the Blues' win that restored their seven-point lead, but also to the disappointment of losing the FA Cup semi-final to their London rivals at Wembley on Saturday.
These are defining moments in the Premier League season - with a huge weekend ahead as Chelsea travel to Everton and Spurs face Arsenal in the north London derby on Sunday.
Man of the match - Diego Costa (Chelsea)
Hazard's best return - the match stats
- Costa's first strike was his 50th in the Premier League in his 85th game - only seven strikers have reached the milestone faster.
- Hazard has scored 15 league goals this season - his best return in a single campaign in the competition.
- Since their return to the top-flight in 2012-13, Southampton have scored more away Premier League goals at Stamford Bridge than any other side (nine).
- Fabregas' assist for Costa's goal was his 103rd in the Premier League - second only to Manchester United legend Ryan Giggs (162).
- Cahill has scored 26 Premier League goals - excluding penalties - the second most of any defender in the competition (after team-mate John Terry with 40).
- Saints conceded four goals in a Premier League away game for the first time since 5 April 2014, when they lost 4-1 at eventual champions Manchester City.
- The Blues have now failed to keep a clean sheet in their past 11 Premier League games.
The Blues are at Goodison Park to face Everton on Sunday (14:05 BST) and the Saints will be at home to struggling Hull on Saturday (15:00 BST).
- 30David Luiz
- 15MosesSubstituted forTerryat 86'minutes
- 7KantéBooked at 40mins
- 4FàbregasBooked at 49minsSubstituted forPedroat 77'minutes
- 10E HazardSubstituted forWillianat 90'minutes
- 19Diego Costa
- 2Cédric Soares
- 14RomeuBooked at 60mins
- 11TadicBooked at 73mins
- 16Ward-ProwseSubstituted forLongat 82'minutes
- 19BoufalSubstituted forRedmondat 68'minutes
- 20GabbiadiniSubstituted forRodriguezat 86'minutes
- Lee Mason
- Shots on Target
Second Half ends, Chelsea 4, Southampton 2.
Goal! Chelsea 4, Southampton 2. Ryan Bertrand (Southampton) header from the centre of the box to the bottom left corner. Assisted by Cédric Soares with a cross.
Nathan Redmond (Southampton) wins a free kick in the defensive half.
Foul by César Azpilicueta (Chelsea).
Substitution, Chelsea. Willian replaces Eden Hazard.
Goal! Chelsea 4, Southampton 1. Diego Costa (Chelsea) right footed shot from the centre of the box to the bottom left corner. Assisted by Pedro.
Corner, Chelsea. Conceded by Oriol Romeu.
Attempt blocked. Nemanja Matic (Chelsea) left footed shot from outside the box is blocked. Assisted by N'Golo Kanté.
Substitution, Southampton. Jay Rodriguez replaces Manolo Gabbiadini.
Substitution, Chelsea. John Terry replaces Victor Moses.
Attempt missed. Pedro (Chelsea) right footed shot from outside the box is close, but misses to the left. Assisted by N'Golo Kanté.
Substitution, Southampton. Shane Long replaces James Ward-Prowse.
Attempt missed. Diego Costa (Chelsea) header from the centre of the box misses to the left. Assisted by Eden Hazard with a cross following a corner.
Corner, Chelsea. Conceded by Fraser Forster.
Attempt saved. N'Golo Kanté (Chelsea) right footed shot from the right side of the box is saved in the centre of the goal. Assisted by Eden Hazard.
Corner, Southampton. Conceded by Nemanja Matic.
Attempt blocked. Steven Davis (Southampton) right footed shot from the centre of the box is blocked.
Corner, Southampton. Conceded by Victor Moses.
Corner, Southampton. Conceded by César Azpilicueta.