Brighton 0-4 ChelseaChelsea moved level on points with second-placed Manchester United after two goals in the opening six minutes put them on the way to victory over a spirited Brighton.
Eden Hazard opened the scoring for the visitors with a neat finish from inside the box and midfielder Willian added a second from 18 yards, after a slick move that he started, to leave Chris Hughton's side facing an uphill task.
The hosts' response was impressive. They should have had a penalty when Chelsea stand-in goalkeeper Willy Caballero upended defender Ezequiel Schelotto, while Israeli striker Tomer Hemed was brilliantly denied by the former Manchester City shot-stopper.
Netherlands international midfielder Davy Propper headed against the post and Schelotto went close after the break as Brighton pushed to get back in the game.
Chelsea were always a threat though and Willian saw a free-kick pushed on to the post by Brighton keeper Mat Ryan before Hazard scored his second with a fine solo effort and Victor Moses' late goal completed the victory.
Chelsea boss Antonio Conte could savour a first league triumph of 2018 for his reigning champions and a strong finish to the game, although he lost defender Andreas Christensen to a head injury in the second half and was already without captain Gary Cahill, keeper Thibaut Courtois and Cesc Fabregas from the start.
But Hughton's concerns continue, despite his team's battling qualities. This defeat means they have now won only one of their last 13 league games.
The Brighton manager tried something different at the back, selecting five defenders to try and halt his side's costly tendency to concede from set-pieces.
But it was from open play where they simply couldn't live with an opponent they haven't beaten since 1933.
Brighton, with a steady central defensive pairing of Lewis Dunk and Shane Duffy, have had a relatively mean defence this term - only the league's top eight sides had conceded less than them before this defeat.
Yet a mixture of misfortune and sloppy play cost them dearly, with Hazard the benefactor on both occasions.
First, Moses' early cross was deflected by Dale Stephens into the path of the Belgian playmaker who quickly found a gap to score the opener. Then Duffy lost possession, allowing Hazard to zip forward and stroke home the third.
There were positives for the Seagulls. They caused Chelsea problems and had VAR been in use they could well have been awarded a penalty when Schelotto was felled.
The industrious Argentina full-back combined well with Pascal Gross down the right flank and will soon have a £14m centre forward to aim for in the shape of new signing Jurgen Locadia.
Like their opponents, goals had been hard to come by for Chelsea recently, with only three in their last five games in all competitions - including three consecutive goalless draws.
This was some way to end the drought.
With striker Alvaro Morata, who had been struggling to score, suspended, Conte turned to Michy Batshuayi who was hoping for an upturn in form after not scoring in the league since netting two against Watford in October.
Conte has reportedly spent much of the January transfer window so far searching for a target man who would make Batshuayi's first-team prospects even bleaker, after only four starts this term. Big centre forwards such as Peter Crouch, Andy Carroll and Christian Benteke have all been linked with a move to Stamford Bridge.
That search might go on because Batshuayi, despite combining well with Hazard for Willian to score the second, failed to score.
But with Hazard and Willian in this type of blistering form, Chelsea can ravage teams even without a free-scoring striker.
Former Everton midfielder Ross Barkley, signed to add attacking threat in the final third, was on the bench and not used at the Amex stadium.
Conte opted to bring on 21-year-old Belgian Charly Musonda instead, and his deft lob created the fourth goal for Moses.
Man of the match - Willian (Chelsea)'I saw important things' - what they said
Brighton manager Chris Hughton, speaking to BBC Sport: "It was a very difficult afternoon for us. The biggest disappointment is that 4-0 was not a true reflection of the game. We did come on to a bit of a game after going 2-0 down and we had decent opportunities, but we are finding it difficult to find the goals we need.
"I thought there were two (penalties that could have been given). We see them briefly afterwards, but when you are Brighton playing at home to Chelsea you need as many things to go for you as possible.
"The second I didn't see well but the first one I thought it was a penalty. I thought we responded well but then we conceded two poor goals - and that made the scoreline not a reflection of the game."
Chelsea manager Antonio Conte, speaking to BBC Sport: "It was an important performance. We started very well and scored quickly, with good combinations. We started with a lot of worries, for injuries and suspensions, but the response of the team was incredible. I am very happy for this. Another clean sheet.
"Today it was a really good performance of the team. We moved the ball quickly, we tried to find the players between the lines, to have good combinations. I saw important things. Now we have to continue."
What's next?Brighton travel to Middlesbrough in the fourth round of the FA Cup on Saturday 27 January (15:00 GMT), while Chelsea head to the Emirates on Wednesday to face Arsenal in the second leg of their Carabao Cup semi-final (20:00 GMT)
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