Centre-back Gerard Pique admitted his Barcelona team-mates will have to be wary of AC Milan striker Zlatan Ibrahimovic when the teams clash in the Champions League quarter-final first leg here on Wednesday. The big Swede spent one season at Barca, where he won the Spanish title, before allegedly falling out with coach Pep Guardiola. He was sold to Milan where he became an instant hit, despite previous spells at their main rivals Inter Milan and Juventus. Although Ibrahimovic\'s Catalan experience went sour, Pique still holds him in very high regard. \"Ibra is a very difficult opponent,\" said the former Manchester United defender. \"He\'s a complete player -- he\'s good in the air, he can play on the floor, he came play with his back to goal and hold the ball up. \"We\'ll have to be very concentrated so we don\'t make any mistakes or leave space when he has the ball. \"It\'s a pleasure to play against him as he\'s one of the best players in the world right now. It was a pleasure to have him at Barcelona and he contributed to our success. \"We will do everything to ensure he doesn\'t play well or score but it\'s not just our defence but the whole team that will have to play well to contain him.\" The two sides met in the group stage, with Ibrahimovic injured for the 2-2 draw at Camp Nou and a scorer in the blaugrana\'s 3-2 success at San Siro. Having played against each other already this season is both an advantage and a disadvantage, according to Pique. \"The best thing is that we know them better but the worst thing is that they know us better,\" he said. \"It will be more difficult because of knowing each other better, because each will know how to attack and defend against the other. \"We\'ll just try to impose our style and score goals, which is very important in the Champions League.\" When Barca were last in town, Guardiola opted to field a three-man backline for much of the game and flooded the midfield. When asked if he would use a similar system this time or revert to a more conventional four-man defence, he was in playful mood. \"We\'re going to play a seven-man defence, everyone under the crossbar,\" he joked, before saying that the match would be decided more my heads than feet. \"These are two teams with great players and the team with the strongest character and mentality will be the one that goes through. \"We need to play lots of football and play well because there will be a big atmosphere and people shouting at us. We\'ll have to do well to dominate the game and then resist in the difficult moments.\" Turning his attention to star player Lionel Messi, Guardiola said his team are simply trying to give the little Argentine the ball as much as possible to let him hurt teams. \"There is a French film called \'Untouchable\',\" said Guardiola. \"Messi likes to play and I prefer to see him on the pitch (rather than training). \"He\'s ready, he\'s fit, and he knows that we\'ve reached the most important part of the season -- the end. \"We\'ve made it to the Champions League quarter-finals again for the fifth year in a row. It\'s a big success for the club so we\'re proud of that. \"We\'re trying, as a coach and as his team-mates, to create the most and best positions for him to receive the ball as much as possible to use his talent. \"For the fans who come here to see the game tomorrow, I\'m convinced they\'re going to enjoy a fabulous and marvellous game.\"