Still 17, Yamal has won the domestic Treble with Barca and also the Euros with Spain over the past 12 months.
De la Fuente, after naming his Nations League squad, said of Yamal: "He is a player with a great future, but he is still developing. We are not seeing the best Lamine yet; he will improve a lot.
"We do not know what this life has in store for him. If he does not get injured, he could become a legend."
Asked about the Ballon d'Or, De la Fuente continued: “It's a process, to deserve the Ballon d'Or... There are other very good players too. These decisions are made in detail. I don't know if he'll win it this year, but I'm sure he'll win it. We'll have to see if it's this season.
"We have to analyse his rivals. The most important thing is that he doesn't focus on a specific objective and that he works as he does and remains humble. If he continues with this dynamic, he'll have many options."