MADRID (AFP) - Barcelona's French striker Thierry Henry has admitted the club will find it difficult to replace the injured Lionel Messi.

The Argentine striker "is very important because he always makes the difference and it is very difficult to play without a footballer like him, even if we don't have any choice," he said in an interview on the club's website.

"Leo is Leo. He has done incredible things this season and it will be very hard for us to make up for his absence," said Henry.

Barca said on Wednesday that Messi, the 2007 World Player of the Year runner-up, would be out of action for six weeks after tearing a muscle in his left leg during Tuesday night's Champions League victory over Celtic.

Henry, who joined the Catalan club from Arsenal last summer, was also critical of his own performances this season.

"I am never happy with my output," said the player, who has scored 13 goals this season. "Like when I played at Arsenal, I am always disappointed when I don't help the team.