Barcelona did strengthen their attack with the addition of Antoine Griezmann, but Messi believes the club should also hand key roles to two of their young starlets.
Fati became the Blaugrana's youngest ever La Liga goalscorer when he found the net in Saturday's 2-2 draw with Osasuna.
Perez, another of the club's youth products, caught the eye during pre-season and has made two starts in the league so far this term.
Messi has apparently called on Ernesto Valverde to trust the two teenagers as Barcelona target success in both La Liga and the Champions League.
The Argentine has yet to feature in 2019/20 because of a calf injury.
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Greg Lea is a freelance football journalist who's filled in wherever FourFourTwo needs him since 2014. He became a Crystal Palace fan after watching a 1-0 loss to Port Vale in 1998, and once got on the scoresheet in a primary school game against Wilfried Zaha's Whitehorse Manor (an own goal in an 8-0 defeat).