As Argentina prepare to face Chile in a rematch of last year's final, Messi's fitness is cause for concern after sustaining a back injury in a friendly last week.
Messi, who has been training alone ahead of the Group D blockbuster, hobbled off the pitch in pain during Argentina's 1-0 win over Honduras in San Juan after suffering rib and back contusions.
However, the five-time Ballon d'Or winner could still play at Levi's Stadium in Santa Clara as Argentina seek to end their 23-year wait for a major trophy.
"We're hoping [Messi] is available for the game," coach Gerardo Martino said in an interview with Chilean newspaper El Mercurio amid his team's six-match unbeaten run, which includes four consecutive victories.
"His presence will be decided last minute, because the lumbar region is very delicate.
"He's very eager to have a very good Copa and to win it. From the way I saw him, I shouldn't be worried."
Chile have a concern of their own after Arturo Vidal hurt his shin in the 1-0 loss to Mexico but the Bayern Munich midfielder is expected to play.
However, Chile's biggest worry is the team's form heading into the centenary edition of the Copa America.
Chile have lost four of their past five matches as Jorge Sampaoli's replacement, Juan Antonio Pizzi, struggles to reach the lofty heights of his predecessor.
One of those defeats came to Argentina, who gained some sort of revenge with a 2-1 World Cup qualifying win in March.
"I am calm, the goals will come," Pizzi said following the defeat to Mexico, having dominated throughout. "There is a level that ensures players will succeed. We must continue to persevere.
"I have peace of mind about how we did things against Mexico. I am calm because the result does not reflect the development of the team."