The San Siro boss is eager to face Pep Guardiola's side on Wednesday, suggesting the Serie A team will aim to stifle the Catalan's grip on possession
The clash will go a long way to determining who tops Group H, with Pep Guardiola's side currently two points clear of second-placed Milan, with the sides having already drawn 2-2 at the Camp Nou in September.
Whilst the Italian boss has suggested that Barcelona are currently the best team in the world, the 44-year-old is hopeful his side can emerge victorious if they capitalise on their opportunities.
"Living these games is the stuff of dreams for everyone at Milan," Allegri told the press.
"Barcelona are the strongest team in the world, but we have to try to beat them by taking full advantage of the chances that we will create.
"When we played in Barcelona [in matchday one] we created plenty and we have to try and do the same."
Allegri has been analysing Barca boss Pep Guardiola's style of play and said it will be hard to dominate the reigning champions.
"It's difficult playing against Barcelona because they have technique and they always vary their ryhthm in matches," the Italian reasoned.
"We will need to be balanced and play higher up the pitch so as not to allow Barcelona too much possession."
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