After the despair of last season, which saw them finish tenth in the Premier League, Chelsea are back with the best – sitting pretty at the top of the table after a remarkable first half of the campaign.
The turnaround under new manager Antonio Conte has been incredible, with the Italian leading his side to 11 straight Premier League wins and a six-point gap at the top.
The club looks rejuvenated, and any hopes of a six-way title fight in a tight Premier League seems wishful – with Chelsea dominating and in danger of running away with the trophy.
Here, we look at why the Blues have taken the league by storm so far.
After winning PFA Player of the Year in 2014-15, many expected Eden Hazard to kick on last season and become one of the best players in the world.
However, his form dramatically dipped as Chelsea’s season crumbled – which led to the sacking of Jose Mourinho a year ago.
The Belgian failed to find the net in the Premier League until April, while his demeanour suggested he was unhappy with life in West London as he sulked around looking devoid of confidence.
With no European football, Chelsea fans feared their star player would seek a move away from Stamford Bridge.
But Conte has worked wonders – relieving Hazard of any defensive responsibilities and ordering him to play with freedom. The 25-year-old has risen to the challenge and looks far happier.
His eight goals are a key part of Chelsea’s excellent season, while he looks back to his creative, scheming best – rivalling any player in the division.
Despite scoring 35 goals in first two seasons at Chelsea, Diego Costa was better known for his short-temper and bad-boy behaviour.
The talented forward arrived with a huge reputation from Atletico Madrid but the rest of the Premier League quickly realised they could tempt the striker into a scrap or two.
Like with Luis Suarez before him, Costa started to believe the powers-that-be were ganging up on him and a move back to Spain seemed inevitable – with Atletico pushing hard.
But Conte refused to sanction his sale and is reaping the rewards. Costa looks leaner, hungrier, faster and mentally tougher.
He is no longer on the back page of the papers for his ill-discipline, but for his glorious scoring.
His 13 goals and five assists have been a major factor in Chelsea’s excellent run – with the 28-year-old netting crucial winners against West Ham, Watford, Middlesbrough, West Brom and Crystal Palace.
Change of formation
Ever since Jose Mourinho’s first spell in charge at Stamford Bridge, Chelsea have been often played with four defenders, five midfielders and one striker.
But Conte found that left his side too defensively vulnerable, with defeats to Liverpool and Arsenal particularly concerning early in the campaign.
The Italian found success at Serie A side Juventus using a 3-5-2 formation and Chelsea have lost just once, to West Ham United in the EFL Cup, since their new manager rolled out his new tactics away to Hull in September.
Chelsea look far stronger defensively and wing-backs Victor Moses and Marcos Alonso offer plenty going forward, relieving Hazard and fellow winger Pedro of defensive responsibilities.
This allows them to counter-attack at a frightening pace, as Manchester City discovered when Chelsea beat them 3-1 earlier this month.
Few teams play with just two central midfielders, but N’Golo Kante makes up for that for Chelsea with his hard work and boundless energy.
The 25-year-old was a revelation at Leicester City last season, helping them lift the Premier League title, before joining Chelsea for £32m.
Since arriving, Kante has impressively shielded the back five along with Nemanja Matic – keeping World Cup winner Cesc Fabregas on the bench.
Kante typifies Conte’s Blues, with his relentless work ethic and undoubted quality ensuring his troops are the toughest side in the league to beat.
David Luiz may not be renowned for his high-quality defending, but he looks a world-class operator at centre-half under Conte.
The Brazilian was brought back by the Italian in order to shore up a leaky backline and he has found a natural home in the middle of Chelsea’s three centre-backs – with Gary Cahill and Cesar Azpilicueta either side.
A talented player, Luiz excels with the ball at his feet and he often sets up Chelsea’s attacking moves with his wide range of passing.
The fact that John Terry remains firmly on Conte’s bench is a great compliment to Luiz – who looks a far better player than the one the club sold two years ago.