Schalke academy coach Norbert Elbert thinks United States youth internationals Haji Wright and Weston McKinnie can develop into first-team pros if they continue to apply themselves.
McKinnie, 18, and Wright, 19, were both promoted to Schalke's first team for their final Bundesliga match of the 2016-17 season. Wright did not play in the match and McKinnie made a 77th-minute substitute appearance in the 1-1 draw.
And Elbert outlined what each player must do to ensure their progress continues.
"I always describe Haji as a bag of surprises," Elbert told Derwesten. "He's yet to have consistency in his game. He has a lot of pace on and off the ball, has no weaker foot, his dribbling is good and he is a threat on goal. But he has to gain some muscle and has to learn more resolve.
"If he takes his chance, Haji can become a big surprise. He is bringing a lot to the table that makes a good striker. Whether he becomes a [first-team] professional is on him and his readiness to assert himself.
"If he keeps working hard and strengthens his strengths and reduces his weaknesses, then he can become a really interesting player. There is still a lot of room for improvement."
Elbert said he sees similarities in McKinnie and former Schalke left-back Sead Kolasinac, who signed for Arsenal on a free transfer on June 6.
He said: "I compare Weston's energy levels to the ones of Sead Kolasinac. Wes is a player that is a benefit for every team. He missed for a long period due to a foot injury last season. He can be pivotal for his team when things aren't going well.
"He is a highly interesting player, for whom I predict an interesting future in professional football. It's hard to call, however, how quickly it develops. I don't want to put any pressure on him.
"He will show grit when training with the [first-team] professionals and challenge some of them in the coming year. He has an incredible force, is strong in the air -- offensively and defensively."
At the end of the Bundesliga season, Schalke sporting director Christian Heidel reserved special praise for McKennie, a midfielder who he said could break into the team on a regular basis next season.
"It was clear to us that we could get him on a Bundesliga level," Heidel said. "We don't [call players up] because it looks good, but because they have what it takes to become professionals."
ESPN FC writer Stefan Buczko contributed to this story.