The Barcelona forward has been in prolific form in the last three months, though the PSG coach is wary of only concentrating on nullifying the Argentine
The Argentine forward has been in incredible form in 2015 and has scored 45 goals in 44 games so far this season to propel the Catalan club to the top of La Liga and into the final of the Copa del Rey.
Messi scored in both clashes with PSG last year, although Blanc is wary of putting all of his defensive eggs in one basket when there are also the likes of Luis Suarez and Neymar to worry about.
“Lionel Messi is unstoppable,” Blanc told reporters. “If he scores 40 goals, he’s had a bad season!
“But we can’t just focus on him. The solution must be collective, man marking doesn’t work.
“We will need to be aggressive defensively but in the good sense of the term, to be able to stop their attackers.”
The coach also piled praise on PSG forward Javier Pastore, who was described by France legend Eric Cantona as better than Messi or Real Madrid forward Cristiano Ronaldo on Tuesday.
“Pastore has huge potential and is becoming an important player for us,” he said of the Argentine. “He has matured enormously in the last six months.”
PSG will be hoping they can replicate their win over Luis Enrique’s side at Parc des Princes in the Champions League group stage in Wednesday’s tie, with the return leg at Camp Nou to be played six days later.