The Italian outfit were beaten 2-0 at the Camp Nou by a Barca side missing Messi through injury, with Rafinha and Jordi Alba the scorers in a comfortable win for the Blaugrana.
However, the Argentine superstar has seemingly made a miraculous recovery from a broken arm to be in contention for Tuesday's return date and has travelled with Ernesto Valverde's squad to Milan.
And Spalletti feels that the prospect of facing the Catalan giants and Messi is a great test for his side, who sit second in the group – just three points off Barcelona at the top – and has called on his players to show their quality against a top-class opponent.
"We can play against anyone and perform the same way," he told reporters at a pre-match press conference.
"The team is doing well, and this is truly the chance to see if we can play evenly against anyone. When we talk about Barcelona, we are talking about the highest calibre of opponent in this game. They have a team mentality and Messi is the cherry on top. All the kids ask for his jersey when they dream of being a footballer. He’s the best.”
The 59-year-old also discussed a potential starting berth for Belgian midfielder Radja Nainggolan, signed from Roma in the summer, as he returns from injury.
Spalletti added: "He’s a complete player, he needs to be evaluated carefully because he’s had injuries, he can also be a defensive midfielder, that is where he started. When we moved him further up at Roma there was a lot of criticism from the media, but then all the criticism disappeared."