Swansea City 0-5 Chelsea

Brazilian playmaker Oscar had plenty of joy at the Liberty Stadium, scoring two first-half goals

• Oscar and Costa both score twice in first half

• Schurrle adds fifth in second half

• Chelsea open five-point gap at top

• Swansea's heaviest defeat of the season

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.

The result was manager Garry Monk's worst since taking over in February 2014 as the Welsh side capitulated to their heaviest home defeat since being promoted to the Premier League in 2011.

It was also the Swans first game since top scorer Wilfried Bony left for Manchester City.

And worryingly for them, their new Portuguese forward Nelson Oliveira proved almost anonymous on his first start in the Premier League since joining on loan from Benfica.

Chelsea now have 52 points from 22 games - although they will see their lead cut to two points on Sunday if Manchester City beat visitors Arsenal.

Jose Mourinho has endured a difficult week as he contests a Football Association charge for misconduct, but the Blues boss had no problems in Swansea and afterwards described his side's performance as the "perfect game".

His team quickly opened the scoring with midfielder Oscar pouncing on a wayward pass by Swansea's Gylfi Sigurdsson to fire a 20-yard shot past Lukasz Fabianski.

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 were full of confidence and took a stranglehold in midfield, as Oscar, Costa and Willian found plenty of space behind Swansea's midfield.

Costa, who scored a hat-trick in September's reverse fixture, rounded off a wonderful team move after 20 minutes, collecting Cesc Fabregas's cute pass to fire past Fabianski from inside the penalty area.

Things soon got worse for 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.

Oscar, 23, came agonisingly close to completing his hat-trick in the second half, but his shot flew narrowly wide of the right-hand post after Hazard had dispossessed Marvin Emnes.

But Chelsea capped their afternoon with a fine team goal when substitute Schurrle tapped home from Branislav Ivanovic's cut-back.

Swansea, who did not have a shot on target in the whole game, are now without a league win since the Boxing Day victory against Aston Villa.

Brazilian Oscar took advantage of an error from Gylfi Sigurdsson to score Chelsea's opener

Costa has now scored five times against Swansea this season

Willian hit the woodwork twice for Chelsea

Chelsea are unbeaten in all eight Premier League meetings with Swansea