Borussia Dortmund coach Thomas Tuchel is confident that United States midfielder Christian Pulisic will continue to be an integral part of the first team despite his young age.

Pulisic, 18, signed for Dortmund in February 2015 as a young prospect, but 10 goals and eight assists with the youth teams saw Tuchel call him up over the winter break in January last year.

Despite his young age, Tuchel believes the Pennsylvania-born player is capable of handling the pressure and will not stop playing him as long as he continues to perform.

"[You've got] nothing to worry about, if you focus on yourself and stay calm and confident and work hard, there's no doubt that you can always start," Tuchel told ESPN FC in an exclusive interview with Raphael Honigstein.

"That's the advantage that comes from treating [Pulisic] this way. We don't look at his age, we don't send him to the team to make ourselves bigger [for publicity].

"There were some doubts, he had some doubts before the season, with all the guys coming in -- Ousmane Dembele, Emre Mor, Andre Schurrle, Mario [Gotze] and Marco Reus. We missed Marco for a long time, and [Pulisic] took his chances.

"It's outstanding because [he doesn't get] injured, he makes almost every training session, that's a huge advantage. He started in many important games. And he deserved it."

Christian Pulisic has already become a key member of the first team despite his young age. Getty Images

Pulisic's swift rise at club level also saw him make his debut for the U.S. national team, and the midfielder has already played 11 times, scoring three goals in the process.

While his stock continues to rise, Tuchel acknowledged that Pulisic's ambition and confidence will see him achieve even more success if he manages to keep his focus.

"I'm very happy with his development this season. Of course, you can't predict these developments, and the way he behaves ... he's a very important part of the team. [It's] outstanding because he could still play for the youth team," Tuchel added.

"In our minds, he's a [regular] player for us and we treat him like a normal guy. Sometimes, you have to look at this piece of paper to believe how young he still is.

"He's very self-confident, Christian. You can see it in training, and the way he plays. He's not nervous, he's very ambitious. It's nice to have him."