UEFA Champions League: Celtic v Barcelona

Last November, Neil Lennon's men sprung a huge shock at Celtic Park when goals from Victor Wanyama and rookie striker Tony Watt secured a famous 2-1 triumph over the four-time European champions.

Messi pulled a late goal back for Barca that night but the Argentinian is set for at least two weeks on the sidelines after injuring his hamstring in Saturday's 2-0 victory at Almeria.

His absence is a major blow for the Catalan giants, with Messi having helped himself to a hat-trick as Barca brushed Ajax aside 4-0 in the Group H opener a fortnight ago to move ahead of Mario Gomez and Filippo Inzaghi by becoming the first player to score four trebles in the competition.

However, coach Gerardo Martino has more than enough in reserve to ensure that Barca will still be favourites.

Spain international Pedro matched his illustrious team-mate's efforts when he took home the match ball as Rayo Vallecano were dispatched 4-0 a week ago.

Messi scored again on Saturday as the Catalan giants claimed a seventh win from as many La Liga matches this term against Almeria, but was then withdrawn.

Meanwhile, Celtic warmed up for the clash in the best possible manner on Saturday when they bounced back from a shock defeat to Morton in the Scottish League Cup with victory at Kilmarnock.

The Scottish Premiership champions survived a fightback from their hosts before prevailing 5-2 as Georgios Samaras fired in a hat-trick.

Weekend goalscorer Kris Commons expects Barcelona to be fully aware of the threat Celtic pose as they attempt to register their first points of the group stage after a battling 2-0 loss at Milan.

"It is going to be difficult but I think it will be very unprofessional of them if they didn't think that we were a threat," the midfielder said.

"For us, it is about staying focused and trying to repeat what we did last year."

Barcelona will once again be without left-back Jordi Alba due to a hamstring problem, while fellow defender Carles Puyol and playmaker Isaac Cuenca are recovering from knee surgery.

Celtic are missing close-season arrival Steven Mouyokolo, who ruptured his Achilles in training before the Milan clash.