The two sides were placed in Group H on Thursday evening alongside Italian giants Juventus and Israeli outfit Maccabi Haifa.
Benfica defender Otamendi played with Aguero at Manchester City and for the Argentina national team, and is also captained by Messi at international level.
Aguero was streaming on Twitch shortly after the draw and he knows better than anyone how physical Otamendi can be. With the World Cup just months away, he sent a jokey message to the 35-year-old.
He said: "PSG, Juventus, Benfica... Otamendi is going to have to put in a couple of kicks. Otamendi is at Benfica, so he's going to have to start hitting and he's going to cross it with Leo.
"Don't hurt Leo, because I'll kill you. The World Cup is coming, Ota."
A third veteran of Lionel Scaloni's side will be involved in the group too, in the form of Juventus winger Angel Di Maria.
Aguero believes Otamendi, nicknamed 'The General', will already have his sights on the former Real Madrid star.
The former Barcelona striker continued: "Oh, you also meet 'Fideo' [Angel Di Maria] in Juventus. Oh, Otamendi. How bad we are seeing it with Otamendi. Otamendi has to hit a good kick to both players. Spicy."
Argentina are currently on a 33-match unbeaten streak and won last year's Copa America.
They also defeated Euro 2020 winners Italy in Finalissima back in June, laying down a marker for this winter's World Cup in Qatar.
Messi will be a key part of any success in the Middle East and he's started this campaign in fine form.
The seven-time Ballon d'Or winner has scored three goals and registered two assists in three Ligue 1 games this term, after managing to find the net just six times in 21/22.
Featured Image Credit: Sergio Aguero/Twitch & Alamy
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