Zlatan Ibrahimovic's awaited return to Barcelona was thwarted after the AC Milan striker was injured in training ahead of the clubs' Champions League game.

The Sweden striker hurt his hamstring during training early Monday and will miss the opening Group H match at the Camp Nou stadium.

Ibrahimovic joined Barcelona before the start of the 2009-10 season in a €60 million transfer that also saw popular Barcelona striker Samuel Eto'o join Inter Milan as part of the deal.

But the outspoken striker left for Milan after his only season with the Spanish champions after a falling out with coach Pep Guardiola.

Milan coach Massimiliano Allegri dismissed questions over whether Ibrahimovic feared playing in front of 90,000 spectators at the Camp Nou.

''He was very relaxed, he was very motivated to play this game, he didn't have any problem in that sense,'' Allegri said on Monday, adding Ibrahimovic's injury was not deemed serious.

''Ibra is a champion, he has shown it throughout his career. Losing (him) for a game like this is obviously a handicap but it doesn't mean we will go into this game with fear - we'll still play valiantly.''

Ibrahimovic never fully adapted to Barcelona's style of play and Guardiola's decision to move Lionel Messi into a more central striker role at times also forced the Swede to play out of position. By the end of his only season in the Catalan capital, Ibrahimovic pointed the finger squarely at Guardiola over the entire episode, which eventually saw him move to Milan.

Guardiola offered only praise for Ibrahimovic, who also spoke positively about the Catalan coach recently.

''Ibrahimovic is one of the world's best players, he's Milan's most important player. It's always better to play against the whole team so it's a shame he couldn't come,'' Guardiola said. ''He's a player on another level. I'm happy for everything he brought for us.''

Ibrahimovic helped guide Milan to the Serie A title after his move last year, a season after helping Barcelona to one of its three straight Spanish league crowns.

While the Swede has always struggled in the Champions League, his absence, coupled with a groin injury to Brazil striker Robinho, leaves the Rossoneri short in strikers with only Alexandre Pato and Antonio Cassano available.

''He couldn't be here - if he could have been here he would of,'' Barcelona midfielder Andres Iniesta said.

''It's a shame he can't be here. I'm sure he is very motivated to play in this stadium, this type of game. Not being able to count on him will always be a handicap for them.''