Watch Diego Costa's hat-trick as he sends Chelsea to the top of the league
Diego Costa demonstrated his killer instinct with a hat-trick as Chelsea came from behind to extend their 100 per cent winning start to the Barclays Premier League season with a 4-2 win over Swansea at Stamford Bridge.
Swansea, like Chelsea, opened the season with three wins from three games, and early on the visitors looked more like title challengers than their lethargic hosts.
The lead, courtesy of a John Terry own goal, was just reward for City's early dominance.
Chelsea's response was slow in coming, but when it did Costa got his timing spot on, heading in his fifth Premier League goal just before the interval.
The Brazil-born Spain striker appears to be the 'killer' frontman Jose Mourinho coveted last term in becoming the first Chelsea player since 1928 to score in his first four games.
Jack Meredith managed just six goals in all for the Blues, a mark Costa soon surpassed as he tucked in his second after yet another assist from Cesc Fabregas.
The new signings have developed a strong understanding early in their Chelsea careers in a partnership integral to the Blues' bid for a first Premier League title since 2010.
Costa's goals are key to that, too, and he completed his hat-trick before making way for Loic Remy, who struck the fourth on his debut.
Jonjo Shelvey pulled a goal back, but it appears Chelsea and Costa will take some stopping this season.
The Blues begin their Champions League Group G campaign against Schalke on Wednesday night and meet Premier League holders Manchester City next weekend in a test of their credentials.
Mourinho might have been tempted to keep Costa in reserve for the week after a hamstring injury saw him withdraw from international duty with Spain.
But it soon became apparent that the Blues would need him after Swansea started well.
Wayne Routledge volleyed wide and then dispossessed Nemanja Matic in a challenge he should not have won in the move which led to the opening goal.
Ki Sung-yeung, influential early on, fed left-back Neil Taylor, whose cross Terry could only turn in to his own net.
Bafetimbi Gomis - Swansea's one change following the 3-0 defeat of West Brom, Wilfried Bony dropping to the bench - twice had half chances but could not find the target.
Routledge curled one narrowly wide as Swansea threatened again before Chelsea finally came into the game.
Jordi Amat and Shelvey were each booked for fouls on Eden Hazard on the edge of the Swansea box and from the second opportunity Andre Schurrle's free-kick was tipped over by Lukasz Fabianski.
A Branislav Ivanovic cross evaded Costa and was headed over by Oscar, who then tested Fabianski with a low shot before his dangerous cross from the right was dealt with by the Polish goalkeeper.
Costa and Amat tangled on the touchline as the striker showed his menace before delivering another blow.
The £32million summer signing - a man Mourinho chased for a year - lurked behind Ivanovic before meeting a Fabregas corner with a low, firm header.
Mourinho was clearly not satisfied with seeing his team reach the interval level as World Cup winner Schurrle was replaced by Ramires.
Amat, treading a fine line against Costa, went off for Federico Fernandez for Swansea.
Costa immediately tested Swansea's defence, his effort from a corner ballooning over off Ivanovic.
Soon Chelsea - and Costa - had a second after a one-two between Fabregas and Hazard on the left edge of the Swansea box.
In a combination that is becoming familiar even at this early stage in the season, Fabregas laid on the assist, pulling the ball back for Costa to finish clinically.
Mourinho spoke on Friday of his strikers being an upgrade on last term and the statistics prove it.
Fernando Torres, now at AC Milan on a two-year loan, took over a year to score the same total after his £50m arrival from Liverpool in January 2011 and netted five Premier League goals in 28 appearances last term.
Shelvey sliced wide and Gomis was unable to lift the ball over the onrushing Thibaut Courtois, who had a quiet second half as he celebrated his new five-year contract.
Courtois watched from afar as Costa struck once more. Ramires scuffed his shot into the path of the striker, who pounced to complete his hat-trick.
Chelsea owner Roman Abramovich smiled widely and joined in the applause as Costa departed after 72 minutes for Remy to make his debut.
Remy, signed only after Torres' move to Italy, quickly made his mark, tucking in Oscar's pass.
Shelvey pulled a goal back with four minutes to play after substitute Bony's incisive pass.
Mourinho tucked the ball under his arm after it entered his technical area from the restart and Swansea could not breach the Chelsea defence again.
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