After drawing with Swansea City and losing to Liverpool, Chelsea found themselves 3-0 down at half-time at Arsenal on September 24, the malaise that had plagued them the previous season apparently refusing to lift.
Chelsea claim English Premier League title
But 10 minutes into the second half, new coach Antonio Conte switched to a 3-4-2-1 formation and Chelsea did not look back, a 13-game winning run laying the foundations for their stunning Premier League title triumph.
"Everything changed at Arsenal," Eden Hazard, who has been reborn under Conte's leadership, told The Guardian earlier this season. "[It was] a turning point. We were losing 3-0, we were beaten, but we got together — coaching staff and players — and determined then things would improve."
A team that had looked on its last legs was suddenly rejuvenated and they laid waste to their rivals in the weeks and months leading up to the turn of the year.
Costa stars as Chelsea move one step closer to glory
Conte, who arrived after overseeing Italy's Euro 2016 campaign, is loath to attribute too much importance to his tactical adjustment at Arsenal, but admitted the defeat has remained in his mind.
"It was a shock, for sure," he said in February. "Usually my teams are not used to conceding three goals in the first half, so it was a shock and a shock I tried to transfer to my players. I don't want this. We worked a lot to avoid this happening again in the future. But this game is always in my mind, always present."
Chelsea's title chances 50-50, says Conte
The changes engendered by that sorry afternoon at the Emirates Stadium were profound.
Ailing right-back Branislav Ivanovic was bombed out of the team and would leave the club in January, along with John Mikel Obi and Oscar.
Emblematic captain John Terry only missed the trip to Arsenal through injury, but he has been unable to get back into the team since then and his storied 22-year association with Chelsea will end when the season finishes.
Chelsea's new-look back three is formed of Gary Cahill, converted full-back Cesar Azpilicueta and David Luiz, who has proved an unexpectedly reassuring presence since his return from Paris Saint-Germain.
Victor Moses, who barely featured under Mourinho, and Marcos Alonso, a £23 million capture from Fiorentina, have thrived in the wing-back roles.
N'Golo Kante, prised from outgoing champions Leicester City at a cost of £32 million, has become the team's heartbeat alongside the elegant Nemanja Matic.
The bewitching Hazard once again looks the player who inspired Chelsea to the title in 2015 and Diego Costa has got his edge back, chipping in with 20 league goals.
The orchestra has been conducted with feverish intensity by Conte, a manic touchline presence whose full-bodied exhortations have delighted those Chelsea fans who sit beside the dug-out at Stamford Bridge.
His impact at Chelsea is reflected in the jealous digs that have been cast his way by rival managers.
Mourinho accused him of over-celebrating during United's capitulation in October and, along with Arsenal manager Arsene Wenger, has branded Conte's side "defensive".
Mourino has also pointed to Chelsea's absence from European competition helping, so next season's return to the Champions League will certainly challenge Conte's working methods.
In the meantime, he has a title to celebrate and an FA Cup final to prepare for, against Arsenal on May 27.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ