SANTA CLARA, Calif. – Warm-ups are over and, in less than 24 hours, Argentina will start their quest for a third consecutive international tournament final. The number one team in the world is no stranger to this sort of atmosphere, but they will have to face the team who beat them in last year’s Copa America final, Chile.

And they’ll probably play against their toughest opponent in the first round of Copa America Centenario without their biggest star.

Lionel Messi has been carrying a back injury for more than a week and arrived in Northern California on Friday, a week after the rest of the squad came to the United States. The lack of training sessions with his teammates and his injury has Argentina looking for alternatives when it comes to playing without Messi.

But, Argentina’s head coach Gerardo “Tata” Martino is not giving up just yet in his hopes of having Messi ready for Monday’s game (10 pm ET; FS1, UniMás).

"We're going to wait until after [Sunday night]'s training session,” said Martino at his pre-match press conference at Levi’s Stadium on Sunday, about the decision to use Messi in the starting lineup.

“The first thing we’ll do is listen to the team doctor, who is the most important voice in this sort of situations, then Leo himself because he's the one who knows how he feels,” expressed Martino. “And after that I'll give him my own perspective in respects to the sporting situation, but the player is the only one who knows how much pain he has.”

Martino seems determined to count with Messi for the whole tournament, although it will be a last-minute decision for Monday.

The former FC Barcelona manager guaranteed Messi is in good spirits and focused completely in the tournament, despite the player’s health and appearance at a Barcelona court for allegedly committing tax fraud (pictured above). Martino also acknowledged he’s going to have the last word in whether to include Messi in the lineup or not, but said it will be a consensual decision.

“Each one of us has the obligation to speak out, because it will be the three of us making the decision,” said Martino. “I'm going to have the last say in it but I can't ignore the player – who happens to be not just any kind of player – and his unique impact in this team, and of course the doctor about the risks we can take.”

If the Argentinean No. 10 is not quite ready to suit up for their Copa America opener, Martino’s expectations are still high for a positive result against Chile.

“The team won't change at all from what we have planned since we left Buenos Aires, because the players in the Argentinean national team understand this is a new possibility [to win a title],” said Martino. “In the last two years they've had the chance to compete in two very important tournaments like the World Cup and Copa America. This will be our third opportunity and we're going to try to take advantage of it.”

Monday’s game could be the first time Argentina lines up without Messi since November 17, when they visited Colombia for a World Cup qualifier. That day, Lucas Biglia scored the lone goal of the match and Messi’s responsibilities were shared between Ever Banega, Ezequiel Lavezzi and Angel Di Maria.

“What we try to do when we build a roster is to have the right substitutes for each position, and clearly there are some differences between Leo and the rest of the players on the national team, but we can't find a reason to differ the way we play,” said Martino.

But despite all this commotion and doubt around Messi, Martino might have given away an inevitable. When asked about winger Nicolas Gaitan’s possibility of filling in for Messi against Chile, the Argentinean head coach expressed his confidence on the Benfica player, in a rather conclusive way.

“When you compare them, it seems as if Gaitan [above] has to play just like Leo, and that's putting a lot of pressure on him. Nico only has to play the way he plays and nothing else,” argued Martino. “Due to the circumstances, he has to replace Leo and I'm not hoping he does anything just like Leo, but I do hope he shows the conditions he’s got.”

Gaitan has only played 13 games with Argentina since 2009 – seven under Martino – but the head coach does not seem concerned about handing the baton to the 28-year old.

“I think he's a very complete player for any of the two positions on the wing and we understand he's the ideal replacement for Leo. But I want to be clear, he only replaces him by name and we hope he plays the same way he does for Benfica,” concluded Martino.