Joe Cole produced a rasping finish in the 21st minute to hand Chelsea a hard-earned victory over Blackburn.
Cole's third league goal this season proved decisive at Ewood Park
David Bentley hit the woodwork with the game goalless before Steven Reid's shot was tipped onto the crossbar by Petr Cech as the hosts looked to draw level.
But Chelsea almost doubled their lead when Frank Lampard's drive was turned on to the post by Brad Friedel.
Roque Santa Cruz was then denied an equaliser by substitute goalkeeper Hilario, who replaced the injured Cech.
It was a vital result for Chelsea on a weekend that brought wins for both Arsenal and Manchester United.
Avram Grant's side ensured the gap between themselves and second-place United remains five points and leaders Arsenal six.
I cannot say it was one our best games but we fought and we got the three points and that is important for us
Blackburn, on the other hand, are beginning to slide down the table having won just one of the last eight league games.
But had they converted their early chances into goals, Mark Hughes' men could well have been out of sight.
Only three minutes were on the clock when Ricardo Carvalho, making his first league start since 11 November, diverted Santa Cruz's goal-bound strike with a fine block.
Morten Gamst Pedersen's subsequent corner flashed across the face of Chelsea's goal and, shortly after firing inches over in the sixth minute, Bentley saw a free-kick from the left come back off Cech's bar.
Another opportunity went begging when Bentley sent Santa Cruz racing clear only for the striker to drag his shot wide of goal.
Blackburn's profligacy was duly punished.
Santa Cruz had a number of opportunities to draw Blackburn level
Carvalho beat Santa Cruz to a ball in midfield and Frank Lampard laid it off for Salomon Kalou. The Ivorian then sent Cole through on goal with a sumptuous curled pass and the 26-year-old crashed his shot high into Brad Friedel's net.
It was the 16th goal Blackburn had conceded in seven games and Hughes will have been furious with the time and space Cole was afforded before his excellent finish.
Andriy Shevchenko should have extended the visitors' lead a minute later when he sliced high and wide from eight yards.
Shevchenko then turned provider as his cross from the left was spilled by Friedel before Blackburn scrambled the ball clear.
At the other end the home side continued to threaten and they were denied a certain equaliser when Cech showed excellent reflexes to tip Reid's shot onto the bar.
But for all Blackburn's creativity in attack their defensive play was desperate and were it not for Friedel's fingertips - tipping Frank Lampard's 25-yard effort onto his upright - Chelsea would have extended their advantage.
They looked set to do just that on the hour mark when Michael Essien powered into the Blackburn penalty area but David Dunn's superb last ditch challenge averted the danger.
From that point on Chelsea focused on preserving their lead and Blackburn accepted the invitation to flood forward.
The likelihood of them snatching an equaliser was raised when Cech was forced off with what looked like a hip injury but his replacement, Hilario, proved an able deputy - springing to his left to turn a 70th minute Santa Cruz header out for a corner.
Chelsea looked to counter-attack whenever possible and Lampard's attempt to record his 100th goal for the club with a low drive was thwarted by Friedel's left hand.
But rarely did the west London club look in serious danger of conceding and they reach Christmas still within touching distance of the top two.
Blackburn manager Mark Hughes:
"I think in the first half we created a good few chances and on another day against lesser opposition they would have gone in for us.
"In the second half we were trying to unlock the door but it is very difficult to draw a Chelsea team out of their defensive positions.
"I thought we had a great deal of positives today. Our play, given the confidence we have lacked on occasions, was good.
"We have come up against one of the top sides in the country and we have done OK."
Chelsea manager Avram Grant:
"I am very pleased with the three points, it is not easy to play here.
"I cannot say it was one our best games but we fought and we got the three points and that is important for us."
BBC Sport Player Rater man of the match: Chelsea's Joe Cole 7.79 (on 90 minutes).
Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.