AC Milan have hinted they could shun their Italian roots when Barcelona visit the San Siro in the UEFA Champions League quarter-final, first leg on Wednesday. Speaking following Saturday\'s 2-1 win over Roma, Milan coach Massimiliano Allegri said there were two ways to tackle Barcelona. \"Either you sit back and try to hit them on the counter-attack, which is difficult, or you do what we did in our home group game and have a go, but we made some mistakes,\" he said. Allegri hinted that he favoured a more positive approach in throwing some caution to the wind rather than adopting a more typical catenaccio (door-bolt) system. In either case Allegri is more likely to turn to his forwards than his defence to try to solve the Barcelona conundrum. The two sides met in the group stages earlier this season and although the scores were close, Barcelona totally dominated in the 2-2 draw in Spain while they also deserved their 3-2 victory in Italy. What those games showed, though, was that Barcelona do concede goals if teams adopt a more offensive strategy. And with Robinho and Maxi Lopez training again following injuries, with the former likely to partner Zlatan Ibrahimovic up front, Milan\'s attacking resources at least appear handsome - much more so than against Roma where youngster Stephan El Shaarawy was called upon. In defence it is a different story as influential centre-back Thiago Silva has been ruled out of both legs with a hamstring pull. It means Daniele Bonera, rather than veteran Alessandro Nesta, who is just back from injury, is likely to play alongside Frenchman Philippe Mexes in the heart of defence. Silva\'s loss cannot be understated despite the reliability of Bonera, who stepped into the breach two years ago at Old Trafford as Milan were crushed 4-0 by Manchester United. Club captain Massimo Ambrosini knows how much Silva will be missed. \"I\'m sorry for Thiago Silva, it\'s an important loss but we\'ll keep going,\" he said. \"Barcelona are the best team in the world but you don\'t need to be a magician to know that. \"They\'ve made their mark on football history but it\'s also a great stimulus to be playing them. We need everyone to make big sacrifices. There\'s not just one player to stop, Barcelona have many weapons.\" Also missing for Milan is former Barcelona holding midfielder Mark van Bommel, as well as forwards Pato and Antonio Cassano. Euro champs in the groove Barcelona have fewer problems, with only French full-back Eric Abidal and Spain striker David Villa missing from their first team regulars. Despite Milan\'s injury troubles, Barcelona goalkeeper Victor Valdes is wary of the Italians. \"They are very dangerous on dead balls and they\'re very good at counter-attacks,\" he said. \"We need to be alert and keep an eye on unmarked players. It\'s a very complicated tie. It\'s vital that we play our style of game.\" Barcelona are also in phenomenal form with the record-breaking Lionel Messi having just become the club\'s all-time top scorer. They have scored twice as many goals as Milan in this competition, including ten in the last round against Bayer Leverkusen. The last time the two sides met before this season, Barcelona beat Milan in the semi-finals before going on to lift the trophy in 2006. Ludovic Giuly scored the only goal of the tie, at the San Siro, meaning Barcelona have won on their last two visits to Milan. The Rossoneri succeeded them as European champions but Barcelona have won the competition twice since, in 2009 and 2011.