She wants to become a professional tennis player, so Julie stays focused. She’s a teen, and if wants to continue to train Julie knows she has to keep her eye on the ball, on and off the court.

Julie has to work on her conditioning. Julie spends hours hitting, hours shadow-playing out points. She haunts the weight room and practices her footwork. She’s even taken up juggling to maintain that “eyes always on the ball” intensity.

Julie eschews most socializing. She won’t let her parents distract her. She’s so far into her head that walking her dachshund is the only pleasure she allows herself.

And when a teammate of Julie’s kills herself and the coach they shared is suspended from their club, Julie doesn’t lose that focus. Others have questions, but “Julie Keeps Quiet.”

Belgium’s submission for this year’s Best International Feature Oscar is a simmering, interior drama about the myopia required to become a professional athlete. Tessa Van den Broeck has the title role, the strokes and the game to make a convincing junior straining with every fiber of her being to make it to “junior pro” with the BTF, the Belgian Tennis Federation.

We never see her play a match. This Leonardo Van Dijl film (co-written with actress Ruth Becquart) lives in Julie’s head and makes us guess what’s going on in there.

Julie doesn’t talk. Even when she’s questioned by classmates, fellow players and the director of the club (Claire Bodson), she is close-lipped.

She has questions of her own, but her solution to every problem, every dilemma facing her in her life, has always been “practice, practice” and “more practice.” She throws herself into preperation, grudgingly accepts a new coach (Pierre Gervais) and carries on.

But something happened. Something was going on. Was it just the pressure of focusing one’s life this narrowly, the fear of not making it, that caused promising junior pro Aline to kill herself? That’s what that suspended coach (Laurent Caron) says.

Julie is young, naive and impressionable, all traits exaggerated by the juvenile nature of sports and making that your life focus. But she’s not stupid.

The script nimbly avoids directly addressing the matter at hand, which the viewer figures out almost from the start. But Van Dijl, making his feature debut, gives us clues in what Julie and the accused Jeremy talk about by phone as she stays in touch with the club pariah. And then Van Dijl delivers a quiet, child-questioning-an-adult scene about why everyone is “stressing out” that will knock your socks off.

“Jeremy, why did she do it?”

That conversation is not loud, explosive or accusatory. It’s as “quiet” as everything else in this film. At times, “mesmirizing” crosses over into tedium in this French and German (they’re studying it in high school) with English subtitles drama.

Who wants to watch an hour of tennis practice? Even players and former players might blanch at that.

But any hint that Julie’s journey to adulthood is stunted by her focus gradually washes away in this smart, tense and above all very “quiet” drama about a tragedy, a possible crime and how one tennis player handles it and what she herself can do about it.

Rating: unrated, adult subject matter

Cast: Tessa Van den Broeck, Pierre Gervais, Claire Bodson and Laurent Caron.

Credits: Directed by Leonardo Van Dijl, scripted by Ruth Becquart and Leonardo Van Dijl. A Cineuropa release.

Running time: 1:40