Barcelona coach Xavi Hernández said Pau Cubarsí can mark an era at the club alongside Lamine Yamal after handing the 16-year-old defender his first start in Sunday's 4-2 LaLiga win at Real Betis.
Cubarsí made his debut as a substitute in the midweek Copa del Rey win over Unionistas de Salamanca, with injuries propelling him into the starting lineup at the Benito Villmarín.
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Yamal, 16, also started the match, setting up the fourth goal, as Barça became the first team in the 21st century to begin a Spanish league fixture with two players under the age of 17.
"He's very well prepared," Xavi said of Cubarsí in his post-game news conference. "He doesn't seem 16 when you speak with him. He is a focused and responsible kid. I don't think he lost a single ball, either.
"He's going to mark an era, the same as Lamine. We are continuing to build a team with young footballers. These are players who we must build the club's future with."
Cubarsí, a Spain Under-17 international, has been at Barça since 2018 and has progressed through the youth academy to become a regular in the B team this season.
Injuries to João Cancelo, Andreas Christensen, Iñigo Martínez and Marcos Alonso opened the door for him to play at centre-back on Sunday as Ferran Torres struck his first-ever Barça hat trick.
The former Manchester City forward scored either side of half-time only to see an Isco brace drag Real Betis back into the game in the second period. Torres then turned provider to tee up João Felix to score the winner in the 90th minute before completing his treble in stoppage time with a chipped finish.
"I place a lot of value on how he has turned his situation in the team around," Xavi added of Ferran, who has now scored 11 goals in all competitions this season and started Barça's last six games.
"When I spoke with him in the summer he transmitted a spectacular message to me, saying he wanted to succeed here. He was very clear about what he wanted.
"He is strong mentally and I am delighted for him because he is an extraordinary guy. He's earned his chance. He is one of the strongest players mentally I know."
The win and the manner of the performance pleased Xavi, who has been criticised this week on the back of the 4-1 Spanish Supercopa capitulation against Real Madrid last Sunday.
Barça have responded to that loss with back-to-back wins which have seen them progress to the quarterfinal of the Copa del Rey and remain within eight points of LaLiga leaders Girona.
"We had the game under control but when they got back to 2-1 we became tense," Xavi said. "Then the equaliser arrived, but we got back on top and played really well with young players and personality.
"It wasn't a complete performance, but it was a great game. We enjoyed ourselves. It's a step forward and I hope it serves as a click."
Barça now turn their attention to the Copa del Rey and a trip to in-form Athletic Bilbao on Wednesday. Villarreal are next up in LaLiga at the Olympic Stadium on Saturday.