Derek Nie, 14, and Crystal Wang, 13, practice at the Maryland Table Tennis Center in Gaithersburg. The teenagers hope to represent the United States at the 2016 Summer Olympics in Brazil. (Mark Gail/For The Washington Post)

Behind the heavy brown door that opens into the Maryland Table Tennis Center, balls ping, zing, pop and pong, hair flies, sneakers squeak and laughter echoes off the walls. Oblivious to the noise, Crystal Wang, 13, finishes her homework in a corner, and then heads over to a blue table. She picks up a rubber-coated paddle, bends her knees, leans into her toes and looks into her opponent’s eyes. She shifts her weight, pulls back her arm and delivers a serve with a feather-light touch.

In a flash, 14-year-old Derek Nie responds from the other side of the net, returning the spinning ball.

Crystal and Derek are no casual players. They are two of the most promising American teenagers in competitive table tennis.

The sport, also known as Ping-Pong, is like tennis, but it’s played indoors on a table divided by a short net. Playing involves a lot of small moves and heart-pounding footwork.

“It feels like a rush,” Derek says.

Derek competes in tournaments around the United States and won his age group at the U.S. Open in Las Vegas last year. (Mark Gail/For The Washington Post)

Crystal, from Boyds, and Derek, from North Potomac, train at the Gaithersburg center almost every day. Derek started playing at age 7, after his older brother got into the sport. Crystal’s grandparents, both of whom played table tennis, introduced her to it at age 5.

“It’s amazing how Crystal and Derek show up at the club ready to play, day after day, week after week, never moping around or complaining and always striving to get better,” coach Larry Hodges says. “They are both also great students. Somehow they balance it all.”

Derek juggles the demands of eighth grade at Robert Frost Middle School, his math team and practicing violin. Crystal, who Hodges says is one of the best female table tennis players of her age in U.S. history, practices every day and still manages to excel in the magnet program at Roberto Clemente Middle School. She competes all over the world, in such places as Japan, Canada, India, China and Austria. Every summer, she travels to China to train.

In 2014, Crystal became the youngest person ever to make the USA National Women’s Team and the youngest to win the under-22 women’s singles competition at the USA National Table Tennis Championships held in December in Las Vegas.

Last year, Derek won his age group at the U.S. Open in Las Vegas. He competes in tournaments around the United States. These days, both players are preparing to compete in the Olympic trials next year.

“My dream is to make the Olympic team,” says Crystal, who also hopes that table tennis will help her get into a good college. She plans to study medicine.

Their successes have been mixed with challenges. In March, Crystal had a big loss. “I was too nervous in my mental game,” she says. “I did really bad, but I just tried to learn from the experience.”

But the challenges provide opportunities to improve in ways outside of their sport. Like how Derek no longer feels that nervous doing oral presentations for his English class. “At least,” he says, “I’m less nervous compared to how I feel at a big tournament.”

And they do have fun along the way. Crystal says she loves making new friends at tournaments. “And,” Derek adds with a laugh, “she really likes to win.”

Kitson Jazynka