LONDON -- Sometimes, a decisive victory is down to luck, nerve and months of practice rolling into one to carry a team toward the finishing line.
Had John Stones not missed two golden chances for Manchester City -- only he will know how he volleyed over from six yards in the 92nd minute -- or had Fernandinho not been similarly wasteful from close range six minutes into the second half, Chelsea might not sit seven points clear at the top of the Premier League.
But, after a pulsating encounter at Stamford Bridge, Antonio Conte's team emerged as 2-1 victors, having capitalised on their key moments and not fluffed their lines when the heat was on. That is why they carry the hallmark of champions as they enter the final stretch of the title race.
Chelsea match-winner Eden Hazard saw City goalkeeper Willy Caballero save his 34th minute penalty -- given after Fernandinho fouled Pedro -- but the Belgian midfielder's luck came in the form of the ball being palmed back in his direction. Hazard held his nerve and buried the rebound.
Just as he could have frozen after missing his initial kick, Chelsea could also have wobbled after Sergio Aguero punished Thibaut Courtois for a poor clearance to cancel out Hazard's 10th-minute opener. But there was no panic, and, if Conte's men are crowned champions, they will look back on this game as the moment they began to close in.
With Tottenham claiming a dramatic and spirited 3-1 win at Swansea, anything but three points after Saturday's 2-1 defeat at home to Crystal Palace would have set alarm bells ringing at Stamford Bridge. But Chelsea claimed the victory required and increased consternation at City by inflicting yet another defeat on Pep Guardiola's team.
This is becoming a season of firsts for Guardiola, but none of the positive variety.
For the first time in his career, the former Barcelona and Bayern Munich coach suffered league home and away defeats against the same opponent. Guardiola has also lost six league games for the first time in a single campaign, having also failed to reach the Champions League semifinals for the first time.
And having seen his team collect just three points from the last 12 available, the City manager is in danger of missing out on Champions League qualification for the first time, with this defeat leaving his fourth-place side just four points clear of Arsenal and Manchester United, both of whom have played a game less; United are due to visit the Etihad Stadium on April 27.
Chelsea may not play with the flair and adventure of Guardiola's City, but Conte's players know their jobs and the system that their manager asks them to play. There is a sense of Chelsea being a well-oiled machine, with consistency that stems from simple and straightforward selection and tactics.
City, in contrast, resemble a jigsaw puzzle that has been emptied from its box, with different players playing in different positions from week to week.
Here, out-and-out winger Jesus Navas was again deployed at right-back against Hazard, while Pablo Zabaleta sat unused on the bench. Vincent Kompany, meanwhile, played for the first time since late January at centre-half, with midfielder Fabian Delph also selected for the first time in a month.
Nine months into his reign as City manager, Guardiola cuts an agitated figure on the touchline and appears to be more confused and uncertain by the game. His players also give the impression that they are also struggling to comprehend their coach's instruction.
In the second half Wednesday, Delph had a look of bemusement as his manager waved arms in all directions. After attempting to take the instruction on board, he nodded and jogged away while shaking his head.
Chelsea's players have no such moments of confusion with Conte, so their energy is focused purely on getting the result and doing their individual job. Simplicity rules, just as it did with Leicester last season as they marched toward the title under Claudio Ranieri, who was present as a spectator for this game.
Moreover, though, there is a connection and a bond between players and manager at Chelsea -- something City appear to lack -- and Conte admitted he had felt like he was kicking every ball on the touchline in an effort to drive his players over the line.
"My look is tired because I feel like I played it tonight with my players," Conte said after the game. "I suffered with them. It's a big win for us tonight. We had moments to suffer, but we suffered as a team in the right way.This part of the season is not easy because the pressure is very tight and dropping moments now is not good. So to win this type of game, at this time of the season, is great."
It is also significant. Tottenham will push Chelsea all the way, but Conte's men passed another test of their resolve against City and will know that this victory will dent the title hopes of their closest rivals as much as it boosted their own.