U.S. men's national team midfielder Christian Pulisic has emerged as a promising young star for Borussia Dortmund despite just turning 18. When he was younger, he trained at Barcelona's famous La Masia academy—though in an unofficial capacity, Sports Illustrated's Grant Wahl writes in his in-depth feature on the rising star.

Pulisic, who grew up in Pennsylvania, had the opportunity to play at La Masia when he was 10 years old. As Wahl writes:

"At age 10, through his father's coaching contacts, Christian trained for a week at Barcelona's famed La Masía youth academy. He was invited back for two more subsequent stints (though not in an official trial capacity)."

A number of star players, including Lionel Messi, Andres Iniesta, Sergio Busquets, Xavi and Carles Puyol, have come up through Barcelona's youth academy.

• The Education of Christian Pulisic: Inside the Dortmund, USA rising star's rapid growth

Pulisic went on to develop further with the respected youth club Pennsylvania Classics, and he joined the U.S. Under-17 residency program in Bradenton, Fla., in 2013–when he was 14. Following a strong showing in a U-17 tournament a year later, he started to earn wider interest and signed with an agent.

He visited Chelsea, Porto, PSV Eindhoven, Villarreal and Dortmund with his father, Wahl reports, before signing with the Bundesliga power.

"I kind of knew it was the right place for me," Pulisic told SI, "and it's been the best decision."

Pulisic debuted for the U.S. men's national team in March, and he features in Jurgen Klinsmann's squad for the team's upcoming World Cup qualifiers against Mexico and Costa Rica. He has scored two goals in Bundesliga play for Dortmund this season.