As things stand, Chelsea look set to run away with the Premier League title.

The Blues finished Boxing Day nine points clear at the division's summit after claiming a twelfth consecutive win, comfortably dispatching Bournemouth 3-0 at Stamford Bridge.

During that club-record twelve-game run, inspired by Antonio Conte's switch to a 3-4-3 formation, the Blues have kept ten clean sheets, conceded just twice and scored a stunning 28 goals - which averages out at 2.3 strikes per game.

Indeed, the west London outfit look unstoppable, especially with Jose Mourinho and Pep Guardiola still finding their feet at Manchester City and Manchester United respectively, Arsenal already buckling under the pressure and Liverpool set to lose Sadio Mane (and potentially Joel Matip) to the African Cup of Nations.

But there is no such thing as unbeatable in the beautiful game and especially in the increasingly competitive Premier League. Even Guardiola's legendary Barcelona side couldn't claim consecutive Champions League titles; even Arsenal's Invincibles eventually lost.

With that in mind and 20 games still left to transform fortunes in the title race, we look at three Chelsea weaknesses that could bring their run to an end - and their title rivals Arsenal, City, Liverpool and United should be looking to exploit.

Slow starters

Traditionally, title-winning sides blow away their opposition in the opening phases of matches, allowing them to batten down the hatches in the second half and save energy for coming contests. We've seen Arsenal, Manchester City and Manchester United essentially kill games within the first half (or sometimes, the first twenty minutes) on countless occasions down the years.

Of course, the Premier League is a little different these days and such sides can't afford to go gun-ho. But nonetheless, Chelsea's impressive run does contain the rather unexpected trend of more goals being scored in the second half than the first - albeit, rather close at 13 compared to 15.

Perhaps more tellingly, only five of Chelsea's last 28 goals have come in the opening twenty minutes - and the most recent was during their 5-0 demolition of Everton at the start of November. At the same time, both of the goals Chelsea have conceded during their twelve-game run were in the first half.

That suggests, despite their league dominance, Chelsea are still starting games cautiously, often seemingly relying on a Cone team-talk to move up a gear in the second half. If an opponent can take the initiative early on with a storming start they have a pretty good chance of getting on the scoresheet whilst the Blues are still trying to find their groove. That could see the west Londoners, not used to being in such a position, quickly become unsettled.

Of course, such an approach would be a risk, but with Chelsea in such great form anyway, there really isn't much to lose.

Azpilicueta in the air

Make no mistake about it, Cesar Azpilicueta is a phenomenal defender - perhaps the best technically in the Premier League. Indeed, the Spaniard can play on either flank and has equally excelled as one of the Blues' wide centre-backs this term, providing speed and quality in the tackle to deal with all matters on the deck.

But Azpilicueta is not a natural centre-back and there's a very good reason for that - he measures in at just 5 foot 10. Of course, how high you jump and how you time your leaps is much more important than your standing height and thus far, the 27-year-old has certainly held his own. His 2.1 successful aerial duels per match is the second-best return throughout the Chelsea squad.

However, that's by no means a resounding average compared to the Premier League norm for centre-backs (Crystal Palace's Scott Dann leads the way with 7.3) and sooner or later, Azpilicueta will be caught out in the air.

That will depend on two things - firstly, a cross that eliminates Thibaut Courtois' reach whilst pinning Azpilicueta down at the far post, and secondly, a towering striker prepared to take advantage by jumping early above the Spain international. There are some interesting candidates on the horizon - Chelsea play Peter Crouch's Stoke City on New Year's Eve, followed by Harry Kane's Tottenham Hotspur.

3-4-3

Currently, 3-4-3 is seen as one of Chelsea's biggest strengths. The formation change following a 3-0 defeat to Arsenal has inspired their incredible run and left the rest of the Premier League struggling to find an answer. It's got the likes of Eden Hazard, N'Golo Kante, Pedro, David Luiz and Diego Costa in their best roles, whilst covering up some of the cracks in Chelsea's squad that emerged throughout the course of last season.

But there is no such thing as the perfect formation in football. Every system has its own strengths but also its inevitable weaknesses and 3-4-3 is no different - it's just a matter of working them out. Take Liverpool during Brendan Rodgers' last full season; a poor run of results saw them switch to a back three and the Reds went 13 games undefeated, winning ten, but eventually the Premier League found a way to beat them.

It's the same with Chelsea. Thus far, nobody's found the right formula and 'matching up' failed for Manchester City and Sunderland. But we're yet to see any side test Chelsea with two up front; can that three-man defence hold out against a direct, little-n-large, old-fashioned strike force?

Whether that's the answer or not, the weaknesses in 3-4-3 will inevitably emerge. It's just a question of the Premier League working them out in time.