LIONEL MESSI is set to be sidelined for up to two months with a hamstring injury he sustained at Real Betis on Sunday.
It means the Argentina star will miss Celtic's do-or-die clash with Barcelona at the Nou Camp on December 11, a game which will have a huge bearing on the Bhoys' European hopes for the rest of the season.
After losing to Ajax last week, Neil Lennon's side need to beat AC Milan in the next game at Parkhead to put themselves in a position to claim second place and qualification for the knockout round of the Champions League, or third spot, which will send Celtic into the Europa League.
Messi limped off after 21 minutes of the 4-1 win after injuring his left hamstring and he underwent further tests yesterday to determine the extent of the problem.
After receiving the results of those tests, Barcelona said the Argentinian is likely to be absent for between "six and eight weeks".
A Barca statement read: "According to the club's medical services, the tests taken on Monday morning by Leo Messi have confirmed that the player has suffered a torn muscle in the femoral biceps of his left leg.
"The approximate time he will be out is between six and eight weeks."
The injury will rule Messi out of both of Argentina's upcoming friendlies against Ecuador and Bosnia-Herzegovina, as well as up to eight matches for Barca. If he is not available again before the end of the year, Messi would sit out four Primera Division matches, the Champions League clashes against Ajax and Celtic, and both legs of the Copa del Rey last-32 tie against Cartagena.
Elsewhere, Germany's Miroslav Klose could be doubtful for their friendlies against Italy and England in the coming days after suffering a shoulder injury on Sunday.