Messi limped out of the clash in tears after sustaining the problem during the first half of the 1-0 win, and tests have revealed the extent of the damage.

It is expected the Argentina international will be out for a month and a half, meaning he is likely to miss around six league games, plus the Copa del Rey semi-final second leg against Valencia and both of Barca's Champions League quarter-final matches.

Barca, who beat Celtic 4-2 on aggregate, are second in the Primera Liga standings, five points behind leaders Real Madrid, while they drew their Copa del Rey semi-final first leg 1-1 against Valencia.

Captain Carles Puyol has blamed the Spanish media for Messi's latest injury setback.

Barca coach Frank Rijkaard left the Argentinian forward out of Barcelona's last game, a 4-2 defeat at Atletico Madrid in La Liga last Saturday, drawing widespread criticism from the media.

Barcelona medical staff announced that they had advised Rijkaard to leave Messi out of the game, yet in the build-up to Tuesday Champions League game the media were unanimous in their calls for Messi to be played.

Now Puyol believes the media must accept the blame for his injury.

"The doctors spoke and said their was a risk of injury and you (the media) put pressure on him to play, saying that he always has to play," fumed Puyol. "Now we're all left to regret the decision.

"On Saturday there was more risk than today, but if he hadn't played and we had got a bad result I'm sure you would have said it was because he wasn't on the pitch.

"Leo's injury is bad news, so now let's see what you have to say about that.

"You've got to leave the doctors and physios to do their job because they know more about these things than you do."