The Barcelona manager recognizes the significance the Argentine can have, but is confident in his team has the ability to cope without him against Celtic.
Cesc Fabregas, Alexis Sanchez and Neymar are considered viable options to replace the injured forward as the Catalans prepare for a chance at revenge against Celtic, who beat them in the group stage last season, on Tuesday.
Martino reminded that Barcelona has played without Messi before and has plenty of players capable of stepping in to fill the void.
"For any team in the world it would be difficult to replace Messi," Martino told reporters. "Even for us, though we’ve got a great squad with outstanding players. We need to play well, even with him missing. I’m not sure it’s a test to play without him, though, we’ve done it before."
Martino discussed his options for replacing Messi up front, but insists he will wait until closer to kickoff to make a decision.
"[Fabregas] is great at linking up with the three behind and he sets his teammates up really well. With Leo we cause the opposition problems in the last 25 meters. Neymar also can’t be ruled out, just as Alexis can’t be. We’ve got various options and we’ll see which one is the best.
"It’s not always going to be that when Messi is out Fabregas replaces him."
Even though Martino was not coach when the Blaugrana suffered a 2-1 loss at Celtic Park last season, he admits Tuesday is a good opportunity to get revenge.
"Everyone is taking it for granted that the game will be like the one last year. We need to be more accurate and faster in our build-up play. It would be good for us to control the ball.
"I don’t think the players want revenge, rather just the chance to put things right. Barca are expected to play well. We’re constantly under microscopic scrutiny. There’s a lot to think about, but we need to focus on what’s ahead, not think about what happened last year."