United States youngsters Zyen Jones and Chris Gloster have been on trial at Schalke, sources at the Bundesliga club have told ESPN FC.

The sources described 17-year-old attacker Jones, a product of Atlanta United's academy, as "definitely an interesting player."

New York Red Bulls product Gloster, also 17, started at left-back for the U.S. at the Under-17 World Cup. Jones has also played for the under-17 team, scoring twice at the CONCACAF U-17 Championship last year.

FIFA rules mean they would not be able to sign a contract to play for Schalke until their 18th birthdays this summer, but they could still join up with the club now, as fellow 17-year-old American Josh Sargent has with Werder Bremen.

In recent times, Schalke have signed U.S. youth internationals Haji Wright, Nick Taitague and Weston McKennie and continue to look at bringing in other young American players.

McKennie has become a fixture in the senior squad and won his first senior U.S. cap in November, while Wright is on loan at second-tier club SV Sandhausen.

Taitague is in his final year with Schalke's Knappenschmiede youth academy, which has developed players including Manuel Neuer, Mesut Ozil, Julian Draxler and Leroy Sane.

In December, McKennie urged young talents to follow in his and Christian Pulisic's footsteps by coming to Germany to take the next step in their careers.

"If it's the right choice, if everything fits, if everything makes sense, I would say come," he said. "You don't want to start in MLS and always have the question in the back of your head if you could have made it over there? I didn't want that."

Last year, Schalke executive Alexander Jobst told ESPN FC he believed there was a "growing number of talents with necessary skills who want to make it in Europe" in the U.S.