The representative revealed that his first impression of the Argentine did not give him much confidence, but was happy that the Ballon d'Or holder managed to prove him wrong and become one of the best footballers in the history of the game.
"When I saw Leo get off the plane I was left with my mouth open. I thought I was in trouble for doing all this for a boy who was so short and thin," Gaggioli told XL Semenal.
"Some associates of mine saw Leo in Argentina when he was an 11-year-old. They said he was very good and I wanted him to come to Spain.
"However, I had to find a team with very specific characteristics, a city where he could continue his hormone growth treatment, which was expensive."
Meanwhile, veteran Juan Sebastian Veron shared a story of the only time he saw Messi uneasy and uncomfortable.
"I only saw him nervous once, and that was before the Greece game when [Diego] Maradona offered him the captaincy.
"It was the responsibility of the leadership that made him uncomfortable, as he realised he had to give a speech to his team-mates."