Chelsea took down another major rival en route to an eighth straight win in the English Premier League by rallying for a 3-1 win at Manchester City, which finished with nine men after late red cards to Sergio Aguero and Fernandinho.Diego Costa was the architect of the turnaround, equalising in the 60th minute with a league-high 11th goal of the season before setting free substitute Willian for the second goal in the 70th at Etihad Stadium. Eden Hazard clinched victory in the 90th.In a chaotic ending, City had two players sent off in injury time – Aguero for a lunge on David Luiz and Fernandinho moments later for pushing Cesc Fabregas by the neck over the advertising hoardings in the ensuing melee. (Also read: Manchester City have steel to win title, says Raheem Sterling)Since losing 3-0 to Arsenal on September 24, Chelsea has picked up maximum points, including come-from-behind wins over title rivals Tottenham and City in the space of a week.Chelsea opened up a four-point cushion over City after 14 games.City took the lead through Gary Cahill’s own goal on the stroke of halftime and will bemoan the failure of the referee to miss Luiz’s apparent shove on Aguero in the 30th when the Chelsea defender was last man.That perhaps explained the late challenge on Luiz by a frustrated Aguero, who has now been dismissed twice this season.The heavyweight clash ended up hinging on a three-minute period when City playmaker Kevin De Bruyne somehow struck the bar from close range before Costa equalized against the run of play.advertisementIt was pure opportunism from Antonio Conte’s visitors, who were under pressure for much of the game but always looked dangerous on the break with the pace of Hazard and the ruggedness of Costa. They scored from all three of their shots on target.There’s no doubt that City’s opening goal was a lucky break, but it was fully deserved after waves of attacks at the end of the first half.Cahill lunged at Jesus Navas’ right-wing cross with his wrong leg and the ball reared up and flew into the top corner. The England defender lay with his face in the turf in despair.Cahill rectified his mistake early in the second half when he cleared off the line a shot from Aguero, who seized on Marcos Alonso’s weak back-pass and rounded goalkeeper Thibaut Courtois.With City pushing forward, De Bruyne crashed a finish off the top of the crossbar from inside the six-yard box after meeting Navas’ cross.Then City fell apart.Fabregas picked out Costa with a superb diagonal pass, and the Spain striker chested the ball inside Nicolas Otamendi and finished low past Claudio Bravo.Costa played an integral role in the winner, beating Otamendi – who dived into the tackle rashly – in the center of the field and setting free Willian, who ran clear and drove a shot across Bravo into the corner.The third goal came from another counterattack as City piled forward, this time Hazard outpacing Aleksandar Kolarov and smashing a finish past Bravo.Much has been made of the renewal of the managerial rivalry between City’s Pep Guardiola and Man United’s Jose Mourinho this season but it seems Guardiola rates Conte as his biggest managerial rival, having described the Italian as a “master tactician” and “maybe the best” manager in the world.This defeat shows just why.