The Argentine insisted the Blaugrana are still in with a fighting chance of progression, while he also commented on the national team, the Bundesliga and two British stars
The Catalan giants crashed to a 2-0 reverse in the first leg at San Siro a fortnight ago, leaving their European fate hanging in the balance despite their favourites tag upon the draw being made in Nyon.
But while the forward is aware of the Rossoneri's defensive aptitude, Real Madrid's victory over Manchester United and the emergence of German clubs this season, he is remaining optimistic about his side's fortunes.
"We can do it. It will be complicated, but we'll get our chances to go through," the 25-year-old said at the launch of 'Team Messi'.
"Never did the Italians play in our box. We will do everything to try to beat them like they did to us. Italian teams are very well organised and leave no spaces at the back.
"Hopefully Tuesday is the day that we can score the first goal from open play.
"Bayern [Munich] and [Borussia] Dortmund are almost certain to be in the last four, they are doing great and they deserve to be [in the knock-out stages]."Madrid are proving to be very strong and are a candidate to win the Champions League, as were [Manchester] United."
A wretched run of form has seen Barca defeated in three of their last five matches, and Messi is determined to bounce back from the jaws of adversity as quickly as possible.
"I've had bad spells before. I've experienced many losses in my time, but I hope to enjoy many more successes like we've had in recent years," he added.
"I'm not sad. Hurt, yes, but not sad. We don't like to lose, but this is the perfect time to bounce back. I have the desire to win every day and I always want more."
Messi also spoke about Argentina's ambitions at World Cup 2014 in Brazil and revealed that winning the international trophy would be the "pinnacle" achievement of his footballing career.
"The national team is going through a good spell, having overcome some complex situations, and we have a lot of room for improvement. We come alive in big games, and we want to book our place in Brazil for the World Cup," he remarked.
"Winning [the World Cup] would be the dream of any footballer. It would be the pinnacle, but we can only talk about that for now."
The futures of Gareth Bale and Wayne Rooney have come under the spotlight recently, as both Premier League attackers have been linked with moves to La Liga, but the No.10 admits he cannot fathom either of the duo pitching up at Camp Nou."They are two top players. You always want to play with the best, but I think it would be very difficult for them to join Barca. They are already at great clubs," he concluded.