FORT LAUDERDALE, Fla. -- Inter Miami coach Gerardo "Tata" Martino has confirmed that Lionel Messi will not be fit for Sunday's game against Florida rival Orlando City, after revealing that the World Cup winner is still dealing with a scar tissue problem suffered while with the Argentina national team earlier this month.

Miami returned to training Friday without Messi and his former Barcelona teammate Jordi Alba, who both left Wednesday's 4-0 win over Toronto FC before the end of the first half, just four days after they skipped the team's trip to Atlanta.

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"Basically, Leo is still dealing with his old scar tissue, and Jordi with muscle pain," Martino said at a news conference Friday. "They are both day-to-day."

The veteran Argentine coach added that he has full faith in Messi to pull himself from games when it's necessary.

"The truth is I have not spoken again to Leo since the match, but his experience gives him the capacity even during a match to know when to stop, when to say enough and when to take precautions," Martino said.

"It seems very prudent at this stage in his career that he does that more than ever. And I say this on behalf of all of us, because we want to see Leo on the pitch for a long time. It is good for me that he is aware that he notices when he has to stop this, like he did in the Ecuador game."

Messi scored the lone goal in 1-0 World Cup qualifying win for Argentina over Ecuador just over two weeks ago, but uncharacteristically left that game before the final whistle and then wasn't in the 18-man squad for the game at Bolívia a few days later.

Messi trained twice after missing the Atlanta defeat -- the team's first since his arrival -- and Martino felt the 36-year-old was healthy enough to give it a go on Wednesday.

"In training he looked good, and he told me that," Martino said. "If there had even been the slightest doubt, he would not have played."

When pressed about the specifics of Messi's scar tissue problem, Martino left that answer for the medical staff.

"I am not a doctor. It bothers him, not hurts him. I do not know why," Martino said.

"It is probable that these scars bother [him] and don't allow him to even be mentally free to play a game. It is difficult. We have all experienced pain when we have hit our scars on the corner of a table and this is like that."

Miami's schedule has certainly been painful since Messi's arrival.

The team played eight games in August, four this month and faces five more in a span of 14 days, starting with Sunday's trip to Orlando.

Three days later, Miami will host the Houston Dynamo in the U.S. Open Cup final, with a chance to lift its second trophy of the season.

And Martino admitted Friday that the schedule might finally be catching up with his team.

"We knew advancing in the Leagues Cup would have a price, especially because we did more movement in the summer and added more players and others who came from European football," Martino said.

"We knew we were going to pay a price somewhere, but we cannot complain; we must see the positive side. We came from a place where we were the farthest from our objectives in the league standings to where we are today, the amount of points we now have."

Where Miami sits today is in 13th place in the MLS Eastern Conference, four spots and five points off the playoffs.

With a win Sunday and some dropped points from teams above, Miami would find itself in with a great chance of making the postseason with five games remaining.

It'll have to try and get that win without Messi and Alba though, and perhaps also without fellow former Barca man Sergio Busquets, who rode a stationary bike during the 15-minute part of practice open to the media Friday.

Busquets has been a rock in the center of Miami's midfield since arriving, starting all 14 games and going the distance in 11.