Goal has previously reported that the Premier League club would be ready to do a deal for Messi should he ever decide to leave Camp Nou.
That is a stance now backed up by Caballero, who is convinced that City have both the desire and the financial means to make the historic transfer possible.
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"That subject is talked about a lot and it's inevitable not to think or speak about it," he exclusively told Goal. "And then when you think that Kun [Sergio Aguero] is at the club and he's such a good friend of Messi...
"But until he's signed or not it's nothing more than a rumour. But yes, I understand that it's possible, because this club has massive economic power. The expensive players that the club has at the moment shows that it can deal with high prices.
"Because of that it seems that they can try to sign Messi if he decides to leave Barcelona. No doubt that City can get Messi, but everything depends on what Leo wants to do."
Caballero earned his first call-up to the Argentina national team in 2014, at the age of 33, and has struggled to get back into the international fold since.
But he says he has already been able to enjoying playing alongside Messi and is clearly excited about the prospect of doing so in Manchester.
"I'm already grateful to the club I'm playing for, but imagine that!" he added. "It wouldn't just be another star in a team full of stars, it would be the best in the world in your team.
"Having the chance to enjoy that in the national team and imagining to be able to have him in my team, it would be the best in the world."