The Manchester City striker recalls how he had failed to notice the media coverage that the 25-year-old was receiving at the time.
"We were talking about shoes, and then he said something," Aguero told DirectTV Sports. "He said his name was Lionel, and I asked, what about the surname?
"He said 'Messi', and then repeated, 'Messi'. I still did not know who he was. Then I read that there was a Messi who was emerging in the team.
"Messi cried with laughter and still cries with laughter when he recalls it. I was 17. Then it was cool between us."
Aguero and Messi shared a room during the tournament and helped Argentina win the competition.