Massimiliano Allegri believes Juventus must be positive at Camp Nou when they begin their Champions League campaign against familiar foes Barcelona.

The Italian champions knocked out their Spanish hosts at the quarter-final stage last season on their way to the final, where they were beaten 4-1 by Real Madrid in Cardiff.

Juventus kept back-to-back clean sheets against Luis Enrique’s side in the last-eight tie, yet Allegri feels his team will need to score to get something out of their Group D opener on Tuesday.

“We’re not yet in peak condition. The aim, as always, is to be fighting on all fronts come March,” he told a news conference.

“Tomorrow we need to score, as to keep a third consecutive clean sheet against Barcelona would be tough.

“We need to play with great enthusiasm and passion as we bid to reach the knockout rounds.”

Barcelona have topped their group in each Champions League campaign since the 2007-08 season.

However, they are a different side to the one Juventus faced back in April; Ernesto Valverde has taken over from the departed Luis Enrique, while Neymar joined Paris Saint-Germain for a world-record €222-million fee.

New signings Ousmane Dembele – drafted in to help fill sizeable the void left by the Brazilian’s departure – Paulinho and Nelson Semedo could all feature for the first time for Barca in Europe.

“It is actually strange to see Barcelona with three new players,” Allegri added.

“They lost Neymar and replaced him with a young man like Dembele, but still today, along with Real, Barcelona are one of the two strongest teams in the world.

“Juventus have changed a lot – and have changed well – and that is a long story about the good work done by the club. Both clubs have moved very well.”