Brazilian midfielder Willian scored an 89th-minute winner as Chelsea edged Everton 1-0 on Wednesday to preserve their seven-point lead over Manchester City at the top of the Premier League.
With City 4-1 up at Stoke City, the defending champions looked poised to trim Chelsea's lead to five points, only for Willian to break Everton's resistance with a crisp low strike at Stamford Bridge.
Chelsea manager Jose Mourinho handed a full debut to January signing Juan Cuadrado, but in the ongoing absence of suspended top scorer Diego Costa, his side struggled to break down Roberto Martinez's Everton.
The home side dominated the game, with Willian and Cuadrado shooting off-target in the first half and fit-again Everton goalkeeper Tim Howard thwarting Eden Hazard, Nemanja Matic and Willian in the second.
Everton's best two chances fell to former Chelsea striker Romelu Lukaku, but he was denied on both occasions by Petr Cech.
Preferred to Thibaut Courtois, the Czech shot-stopper jutted out a foot to thwart his former team-mate in the first half and then produced a stunning point-blank save to deny the Belgian in the 68th minute.
Chelsea thought they had broken the deadlock in the latter stages when a shot from Matic flicked off Branislav Ivanovic and went in, but it was ruled out for offside.
Mourinho's men continued to press, however, and after Everton's Gareth Barry had been shown a second yellow card following a heated melee, Willian snatched the winner.
Howard left his line to punch clear a high cross, but could only send the ball to Willian, who drilled a controlled shot through a crowd of players and into the bottom-right corner.
- Aguero at the double -
City's victory at the Britannia Stadium, constructed around a brace by Sergio Aguero, ended a run of four games without a win as they returned to winning ways following a disappointing 1-1 home draw with Hull City.
City were looking to record a first win at Stoke in the league in seven attempts and they took a 33rd-minute lead when Aguero ran onto a punt from James Milner and fired into the bottom-left corner.
Peter Crouch equalised five minutes later, stooping to head home a Marko Arnautovic cross at the far post, but Milner put City back in front by heading in a cross from Samir Nasri early in the second period.
Aguero scored from the penalty spot after Geoff Cameron was adjudged to have fouled David Silva before Nasri got on the score-sheet in the 79th minute by surging to the edge of the box and slamming home.
Elsewhere, Manchester United climbed above Southampton and Arsenal to reclaim third place by winning 3-1 at home to second-bottom Burnley, with early substitute Chris Smalling scoring twice.
Stung by accusations his side had played "long-ball" football in their 1-1 draw at West Ham United on Sunday, United manager Louis van Gaal saw his team take a sixth-minute lead courtesy of Smalling.
The England defender had only been on the pitch for a matter of seconds after replacing the injured Phil Jones when he scored with his first touch by heading home from a corner.
Danny Ings headed in Kieran Trippier's inviting cross to equalise six minutes later, but another Smalling header restored United's lead in first-half injury time before Robin van Persie added a late penalty.
Southampton fell to fourth place after a 0-0 draw at home to West Ham in which visiting goalkeeper Adrian was sent off in the 61st minute for handling the ball outside his area.
Source: AFP