Chelsea extended their lead over Manchester City at the top of the Premier League to five points after hammering an abject Swansea City.
The visitors led after just 50 seconds thanks to Oscar's 18-yard strike, before Diego Costa scored twice in 15 first-half minutes.
Oscar completed his brace moments later and Andre Schurrle finished the rout in the second half.
Swansea, who stay in ninth place, are now winless in four league games.
Chelsea, who have 52 points from 22 games, will see their lead cut to two points on Sunday if Manchester City beat visitors Arsenal.
Jose Mourinho's side quickly opened the scoring in Wales with midfielder Oscar pouncing on a wayward pass by Swansea's Gylfi Sigurdsson to fire a 20-yard shot past Lukasz Fabianski in the first minute.
Sigurdsson nearly made amends straight away when his rasping shot from the edge of the area struck Petr Cech's right-hand post.
But the visitors continued to press and took a stranglehold in midfield, as Oscar, Costa and Willian found plenty of space behind Swansea's midfield.
Costa rounded off a wonderful team move after 20 minutes, collecting Cesc Fabregas's cute pass to fire past Fabianski from inside the penalty area.
Chelsea were rampant and Costa nearly doubled his tally within a minute of his first, but his curling shot from the edge of the area flew over the bar as the Swans' defence backed off.
Willian was next to try his luck when he collected Fabregas's pull-back to smash a right-footed shot against the post after 25 minutes.
Swansea were dealt a further blow when winger Wayne Routledge hobbled off with an injury, to be replaced by striker Marvin Emnes.
Things soon got worse for Garry Monk's side as defender Federico Fernandez gifted Costa his second on the half-hour mark.
The Argentine's attempted back-pass to Fabianski was picked off by the Spanish striker, who calmly slotted the ball past the Polish goalkeeper.
Brazilian playmaker Oscar completed his brace a minute later when he found space in the Swansea box to shoot into the top corner.
Willian nearly made it five before half-time but he thumped a 15-yard shot against the bar after Costa had rounded Fabianski after yet another Chelsea break.
Swansea, who have not beaten Chelsea in the league since 1981, were playing their first game since top scorer Wilfried Bony left for Manchester City.
Monk's side were more resolute after the break but failed to muster any goalscoring opportunities.
Indeed, Portuguese forward Nelson Oliveira proved almost anonymous on his first start in the Premier League since joining on loan from Benfica.
Chelsea slowed the pace in the second half, with the game broken up by a raft of substitutions.
Belgian Eden Hazard almost stretched the Blues' lead midway through the half when he forced a smart save out of Fabianski with a powerful shot from 20 yards.
Oscar, 23, came agonisingly close to completing his hat-trick soon after, but his shot flew narrowly wide of the right-hand post after Hazard had dispossessed Emnes.
But Chelsea capped their afternoon with a fine team goal when substitute Andre Schurrle tapped home from Branislav Ivanovic's cut back.
The result leaves Swansea without a league win since the Boxing Day victory against Aston Villa.
Credit: BBC
