If, as expected, he returns to a reserve role this weekend, D.C. United defender Ethan White won’t pout. In two starts last week, the Bethesda-Chevy Chase High School graduate took a considerable step forward in his blossoming career.

He proved to himself — and to an intrigued coaching staff — that after just two seasons at the University of Maryland and an injury-delayed preseason, he is capable of meeting the demands of professional soccer.

“It’s good to know that I can possibly step in and fill in for anybody,” White said Tuesday. “I still have some work to do, but whenever my time is called, I’ll step in. I’m content with where I am at the moment.”

White, 20, made his debut last Wednesday with a starting assignment against the Philadelphia Union in a U.S. Open Cup qualifier at Maryland SoccerPlex that featured several reserves. It was a secondary test, and he performed well during 90 minutes of regulation and 30 more in overtime, before United won on penalty kicks.

On Saturday, with the Los Angeles Galaxy in town for a regular season match at RFK Stadium and starter Perry Kitchen back from the U.S. under-20 national team, White was planning to return to the bench. At 3 p.m., he received an urgent call from Coach Ben Olsen: Kitchen had fallen ill and White would have to start again.

“I was very nervous,” said White, comparing the radically different settings and crowd sizes, not to mention the presence of Galaxy stars David Beckham and Juan Pablo Angel.

After playing against Philadelphia, “I felt like I was a step closer. I wasn’t sure if I was ready enough,” he added. “I felt like I had battled enough to make a step up in the coaches’ minds. Then when Perry got sick, my chance came and I jumped on it.”

White offered quality work, helping to neutralize Angel, one of MLS’s most accomplished strikers. With Kitchen healthy this week, White seems likely to step aside for Saturday’s match at Toronto FC.

“Physically, he’s pretty special,” Olsen said of the 6-foot, 183-pounder. “We asked him to be an extremely competitive, hard defender that plays simple. I told him he can have a long, very good career by just being a tough-nosed defender.”

White’s athletic ability earned him honors in other sports. At age 12, he won the pentathlon and finished second in the 1,500 meters at the AAU Junior Olympics.

Technically, White, who left Maryland in December, is a rookie. But his ties to United run deep. Growing up in Kensington, he attended matches with his family. He vividly recalls watching from RFK’s upper deck three years ago when United played the Galaxy. His favorite player was Olsen. His older brother, Nigel, was a United guest player for two years.

When Ethan was 16, he joined United’s youth academy, an elite program designed to prepare players for college and pro careers. One summer, he trained with United’s first team.

Last December, after completing a second season for the Terrapins, he turned pro. As a graduate of United’s academy, White was exempt from the MLS draft.

In the second half Saturday, with White, goalkeeper Bill Hamid (Annandale) and midfielder Andy Najar (Alexandria) in the match, United became the first club in league history to field three homegrown players at once.

“It definitely relieved some stress” staying with United, he said. “I didn’t have to worry about where I was going. I knew I was going to be at D.C. I knew the coaches, I knew some of the guys on the team. It was a comfortable transition.”

White had a calf injury during the preseason, but after regaining his fitness, he displayed potential. United’s staff took a long view, figuring to use him in non-league matches and spot duty during the regular season.

But on Saturday, with Kitchen stricken and first-choice reserve Rodrigo Brasesco nursing an injury, White received the call. Late in the first half, with Hamid caught in the middle of the penalty area, White stabbed a shot off the goal line to prevent a two-goal deficit.

“He wants to be in real games,” Olsen said. “He has a good confidence about him. We’ve [told] him now, it’s not a one-time deal; this is the professional level. It’s not good enough to play one good game and then have a game where you are not so good. Getting his head around having that type of performance consistently is always the trick with young guys.”