Mastrángelo, a chocolate maker by profession, made it his hobby to keep track of each of Messi's goals, an achievement his grandson Julián has announced on social media, catching people's imagination including the striker himself.
Messi, who recently celebrated winning the Copa America with Argentina, recorded and sent a video message of thanks.
"I wanted to have scored all the goals that Messi did," Mastrángelo told Reuters. "I followed him and always kept following him. I always followed the games and if I didn't have time to watch them, my grandson would tell me about them."
The centenarian, who doesn't like to use cell phones or computers, wrote down on sheets of paper the name of the rival team, the date and the number of goals, recording more than 700 scored by Messi over the years.
He likes to go over it with the help of a magnifying glass.
When the story reached Messi in the middle of the Copa América, Mastrángelo's grandson received a call from a relative of the star to thank him and send the video.
"Hello Hernán, obviously your story came to me. It seems crazy to me, not even I have the goals saved in that way. I wanted to send you a big hug and thank you for what you are doing," Messi said in the recording.
In his house in Carapachay on the northern outskirts of Buenos Aires, Mastrángelo was surprise and emotional when he received the message.
"I don't think there can be many people to whom he (Messi) has said something like that," he said.
