Echeverri scorred twice to lead Argentina to a 6-0 triumph in their opening game of the tournament.
The 18 year-old will join City after the campaign, after his loan with River Plate was cut short at the beginning of this month's winter market.
"It's an immense joy," he told TyC Sports. "Everyone played a great match, we had been preparing for this evening for a long time. We knew how difficult the rival we would face was. It's a source of pride, it's something historic. Now we won't give up and we'll continue to improve."
Echeverri also scored a hat-trick in the 3-0 U17 World Cup semifinal win against Brazil.
He added, "First in the Under-17s, now here... You are always motivated to play against Brazil. Being Argentinian, you always want to beat Brazil."