3 takeaways from Chelsea's ruthless away win at Manchester City

Chelsea scored all four goals as Manchester City's profligacy was punished by a clinic of counter-attacking, disciplined, and piercing football from the visitor on Saturday.

City possibly shaded the first half, and Gary Cahill's woeful own goal gave the host the advantage shortly before the break. Goals from Diego Costa, Willian, and Eden Hazard in the second stanza, however, kept Antonio Conte's ruthless ranks atop the Premier League with a 3-1 win.

Pep Guardiola's side imploded in the final seconds. Sergio Aguero's egregious, high, two-footed tackle on David Luiz was rightly met with a red card, and in the subsequent scuffle, Fernandinho received his marching orders for his rough treatment of Cesc Fabregas.

Related - Look: Aguero's horrific tackle on David Luiz incites last-minute brawl

City, now missing two of its most influential players for at least three matches, is left to pick up the pieces going into the busy festive period, while Chelsea's buzzing with an eighth consecutive victory.

Here are three takeaways from Chelsea's professional 3-1 triumph at the Etihad Stadium:

Missing Matic could be bad news

In a shock selection revealed an hour before kickoff, Fabregas was chosen ahead of Nemanja Matic in the starting XI. The latter didn't even travel with the matchday squad, prompting talk that he had an injury well before the bout that Conte chose not to disclose at Friday's pre-match press conference.

Making just his second league start and first since Sept. 24's 3-0 loss to Arsenal, Fabregas did well number-wise: He launched the delicious long ball that set up Costa's strike, and let Fernandinho shove him before appearing to deliberately step backwards over the advertising hoardings to get the Brazilian sent off.

But when it comes to defensive work, he can have the legs of a grand piano. In the opening period, he covered plenty of ground - albeit with no urgency, allowing David Silva to find pockets of space and select passes with ease.

While Fabregas' inclusion paid off this time, N'Golo Kante will have a lot on his plate for however long Matic is absent. Chelsea has proved susceptible to a high press from Liverpool, Arsenal, Tottenham Hotspur, and City, and other teams will be further encouraged to use this formula while Fabregas is ambling around the pitch.

City's wastefulness punished

City started the second half in the ascendancy, making continual inroads down the right through Kevin De Bruyne and the much-maligned Jesus Navas, and calling several Chelsea players into last-ditch blocks and interceptions. One from Victor Moses, sliding in to deny Aguero a surefire goal just before Willian's tally, was vital.

The match ultimately hinged on an earlier miss from the usually faultless De Bruyne, though. The superb Silva, who was his sparky and inventive self, squared a low ball across to the Belgian and, with the goal gaping, he managed to clip his shot off the bar and over from merely 4 yards out. It would've been 2-0.

With Aguero potentially set for a four-match suspension given the reckless nature of his challenge on Luiz, he may be out until New Year's Eve in Liverpool. He's already been punished by the Football Association for violent conduct on West Ham United's Winston Reid, so Guardiola must be tempted to rush Gabriel Jesus into action. The Brazilian teenager was watching from the stands ahead of his January switch.

Costa now a team player

No longer does Costa take the field on a one-man mission to needle defenders, berate the referee, and, on occasion, get on the scoresheet.

The Spaniard is transforming into the complete forward under Conte. Rather than looking for an opportunity to go down and win a foul, he's picking out openings to set up his teammates or find space, and, for his goal, shrug off centre-halves before confidently sliding the ball home.

From this season to last season, it's night and day for Costa:

The entire Chelsea attack was callous and proficient Saturday, scoring with each of its first three shots on target. With each week, Conte's squad is strengthening its status as the team to beat.