Marc Bartra has said Barcelona's La Masia youth academy can be a scary place for youngsters hoping to make it at Camp Nou.
La Masia has produced a number of the world's best players during the last 20 years, including Lionel Messi, Xavi and Andres Iniesta, and is widely held up as an example to follow when it comes to youth development.
However, Bartra, who spent 14 years at Barca before leaving in 2016, does not remember his early years in the academy fondly.
"The scariest part is that you know that, even if [the coaches are] just a little unhappy with you, they'll bring in someone else," he wrote on The Players' Tribune. "This is the Barca academy -- every kid in the world wants to play there.
"You'd see these talents come not just from the whole of Spain, but from Mexico, Israel, Brazil, Germany, wherever. And you'd think: If I don't do well, next year they'll be here, and I'll be gone.
"Trust me, that's pressure. Especially when you're 10 years old. You don't really have the maturity to deal with it. You're living the life of a seasoned professional, yet you're still a kid. And honestly, I don't remember enjoying it much."
Barca's recruitment of youth players from around the world eventually saw them hit with a transfer ban in 2014, which has subsequently seen them re-focus their efforts on signing the best young players in Spain.
Despite the competition and the stress, though, Bartra does also harbour happier memories from his time at La Masia.
"I loved it when we got to train with the ball, or when I could play with my brother [who was later released from the academy]," he added. "But on a day-to-day basis, having to train hard and study to get good grades, well, I found it very difficult."
Bartra, now 27, made his first-team debut for Barca in 2010 and went on to make over 100 appearances for the club before signing for Borussia Dortmund in 2016.
After 18 months in Germany, and after being injured when a bomb exploded near Dortmund's team bus in 2017, the Spain international returned to La Liga with Real Betis earlier this year.