Manager Jose Mourinho paid tribute to his side’s mental strength after the match.
"The performance was brilliant - we played very, very well. Tactically, we were always in control against a very difficult team," the Portuguese manager said.
"The team did collectively very well - we were mentally very strong.”
One point of concern was the six bookings the team received including one to midfielder Frank Lampard who will miss the next game in Germany against Werder Bremen.
The Germans, 3-0 winners in Sofia, stand three points behind the Blues but two points ahead of a Barcelona side they must nonetheless still face at the Nou Camp.
Something to shout about
A former Porto player under Mourinho, Deco, scored the opener in the third minute with a sweetly-struck drive which delighted the 95,000 crowd.
On 52 minutes, Lampard, just onside, missed a regulation chance on goal before recovering and scoring a wonder goal with an audacious chip from the by line.
Barca regained the lead when Ronaldinho came alive on the left to dink a ball low into the Chelsea box, where Gudjohnsen gleefully smashed home from four yards after 57 minutes.
It looked to have sealed the win before Drogba stepped up in injury time to leave the Catalans campaign on a knife edge.
B for Bayern
In group B, Bayern Munich qualified for the last 16 of the Champions League with two games to spare despite firing blanks in a 0-0 group B draw with Sporting Lisbon at home.
While in the other fixture Inter Milan kept their hopes alive with a 1-0 win over Spartak Moscow thanks to a goal from Julio Cruz.
The Italians leap frogged Sporting with the win in the two team fight for second place, while Spartak can already start planning for next season.
Reds and PSV through
The progessing sides in Group C were confirmed as both Liverpool and PSV Eindhoven won their respective fixtures to book their places in the knockout stages.
Five time winners Liverpool side defeated Bordeaux 3-0 at Anfield.
Spanish midfielder Luis Garcia further enhanced his reputation as a European specialist with two goals to set up the comfortable victory.
Captain Steven Gerrard scored his first of the season to complete the rout.
Carlos Salcido celebrates PSV's
While Ronald Koeman’s PSV 2-0 victory was aided by the red card shown to Galatasaray’s Croatian defender Stjepan Tomas.
PSV Eindhoven shot into the Champions League knockout stages after earning a 2-0 victory over 10-man Galatasaray here on Tuesday night.
Koeman singled out Tomas' red card as the key point in a match which left his Dutch side lying second to Liverpool in Group C on goal difference.
"Super, it was a deserved win and a little easier than anticipated. The Turkish side didn't leave us much space but then came the turning point with Tomas' sending off,” he said.
"We really capitalised on our numerical superiority."
Action from Group D saw Valencia come back twice to earn a 2-2 draw with Ukrainian side Shaktar Donetsk to seal their passage to the next round.
Roma look most likely to advance with the Spaniards are their 1-1 draw with Olympiakos put them five points ahead of the Greeks with two matches to play.
Franceso Totti: Suck on this
Julio Cesar’s opening goal lifted the spirits of the Greek club, before Roma golden boy Franceso Totti scored an equaliser to put the Italians on the verge of qualification.