Ancelotti hails two-minute turnaround
Having lost one and drawn three of their previous five league games since the impressive 3-0 win at Arsenal on November 29, as well as going out of the League Cup against Blackburn Rovers, another defeat would have handed the title initiative to their rejuvenated London rivals and champions Manchester United.
United's defeats by Aston Villa and Fulham prevented Chelsea's draws doing too much damage but with Alex Ferguson's side at home to Wigan Athletic on Wednesday and with key striker Didier Drogba about to disappear to the African Nations Cup, it was looking anything but a season of good cheer for coach Carlo Ancelotti.
However, with time beginning to ebb away, Chelsea turned the match and possibly their season.
Drogba levelled with a 73rd-minute header before a Chris Smalling own goal gave Chelsea the win that re-opened their five-point lead over United, albeit with an extra game.
"I think with this victory, this performance, we have finished a difficult period," Ancelotti told reporters.
"It is one of the most important results because it arrived at what was not a good moment for us. I am very happy with the reaction of the team. We reacted as a team not as individuals."
Last season Chelsea lost two and drew four of their eight league games from November 22 to January 11, leading to the sacking of coach Luiz Felipe Scolari soon afterwards and allowing United to take a lead in the title race they never relinquished.
Ancelotti's position is safe but he knows improvements have to be made if Chelsea are to challenge for both the Premier and Champions League titles over the second half of the season.
"It was not a good December for us but December is finished and we have to look forward," he said. "We have to do better in January."
The fixture list does not look too daunting either, with games against Hull City, Sunderland, Birmingham City and Burnley next up, but this season has thrown up plenty of surprises already and Ancelotti will have to take on those sides without four important players.
Drogba, Salomon Kalou, John Obi Mikel and Michael Essien are all away on Nations Cup duty from this week, leaving a large hole in their midfield and attack.
"We did well without Drogba in the Champions League and we can do well without him in January," Ancelotti said.
February, however, was the month on the mind of one interested observer in the Stamford Bridge directors' box on Monday as Jose Mourinho was given plenty of food for thought ahead of his Inter Milan side's Champions League first knockout round tie with his former club.