Messi, the prolific Argentina forward, has tried to make Barcelona forget about its disappointment in Scotland by maintaining his remarkable run of scoring form.
His double in the 3-1 win at Real Zaragoza on Saturday took his 2012 tally to 78 in 2012, moving within seven of former Germany striker Gerd Mueller's all-time record of goals in a calendar year, set in 1972. Last week, Messi scored another double to move past Pele into second place (75 goals in 1958).
However, coach Tito Vilanova has made a point of saying his squad's success is more down to teamwork than the individual brilliance of its star player.
"We need all of our players, because just one man can't win you the match," Vilanova said.
Barca has already spoken of Messi's hunger to beat Raul Gonzalez's tally of 71 goals as the all-time highest scorer in the Champions League. Currently, Messi is third with 54, behind Ruud van Nistelrooy (56).
Vilanova welcomed back the central-defensive pairing of Gerard Pique and Carles Puyol at the weekend, which should shore up a back line that looked exposed against Celtic.
A stoppage-time winner in a 3-2 victory over Shakhtar kept Chelsea in contention last time out, but there remains the genuine possibility that the English team could become he first reigning champion to fail to make the knockout stage.
The Blues are in their first rut of the campaign, having won just two points from their last four Premier League games.
"We've been in this position before. For some reason, November for our club is a bad month and it seems to again be the case this year," Chelsea manager Roberto di Matteo said. "We have to try and address that."