The two Argentines are currently on international duty as they try and take their country to the World Cup.
Both have provided some lethal firepower over the years for their nation, scoring 112 goals between them.
And they are good friends too, rooming up since they were 17.
However, when asked about their relationship on the show 'Santo Sobado', Aguero was brutally honest.
The 32-year-old admitted that they were like "an old married couple" and that Messi was "a big whining".
He said: "I always fall asleep with the TV on and the next morning he's always complaining."
Aguero also detailed how they were complete opposites when it came to preparation.
The Manchester City ace admitted he had a more relaxed outlook on life compared to Messi, who was always in a rush.
He added: "For example, we get back to the hotel at 19.30 and we're eating at 21.00.
"There's time. But Leo's in the shower straight away and ready. I'm there in my boxers and talking on my phone...
"Time passes and with half an hour to go, he starts: 'We're eating a 21.00, in 30 minutes...'
"I'm still there on my phone and he's going: '10 minutes to go. We always arrive late. We've been here for an hour...'
"And then I get ready. The bad vibes start and he doesn't like arriving late!"
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Over the summer, Messi demanded that be able to leave the Catalonian club only to be told by Barca president Josep Maria Bartomeu that it was impossible.
The only way he could depart was if someone splashed out €700m on his release clause - which looked improbable at best.
Messi would have had to take Barcelona to court, something the six-time Ballon d'Or winner did not fancy doing so and risk tarnishing his legacy.