Barca confirmed that Messi will face up to six weeks on the sidelines after tearing a thigh muscle on Tuesday.

The dexterous Argentine suffered the injury during a run-in with a Celtic defender as he left the pitch in tears a few minutes before the break.

"Messi's injury affected the team tonight. He has been injured before and it's a very sad moment," Rijkaard said after the game at Nou Camp.

Messi re-aggravated the same injury for the fourth time in three seasons and the Argentina international will miss the friendly against Egypt on March 26th.

Rijkaard admitted that the Catalans were facing a tough opponent despite winning both ties.

"Celtic played well and were getting better as the game went on. We started well and scored an early goal. Celtic were playing with confidence and giving us a hard time as usual," added the Dutchman.

Lesson

Barca skipper Carles Puyol said that Messi's injury is a lesson for those who blamed Rijkaard after resting the injury-ridden winger in the 4-2 defeat to Atletico Madrid last weekend.

"Messi’s injury is a lesson to everyone, you pressured for him to play against Celtic and now look what has happened. What you have to do is show more respect for the medical staff and the coach," he told reporters.

"The coach took the decision to rest Leo (against Atletico) at the Calderon because there was a risk of injury. Now I suppose you will be criticizing the medical staff because he is injured."