After his first-round victory seen here, suburban Washington native Francis Tiafoe stumbles to a loss in the second round of the Junior French Open. (Getty Images)

PARIS — It’s the rare teenager who makes his debut at a Junior Grand Slam tournament as the No. 1 seed.

Maryland native Francis Tiafoe, 16, was that rare teen at this year’s Junior French Open, taking the venerable clay courts at Roland Garros for the first time in his life as the competitor the 63 other boys most wanted to beat, the youngster whom the media wanted to interview and the American deemed most likely to re-stake the country’s claim on tennis supremacy.

Tiafoe may do just that one day.

But he fell short Monday, losing in the tournament’s second round to an unseeded German who was far bigger, hit harder and ultimately coaxed Tiafoe into a rash of uncharacteristic errors.

The result was a 2-6, 6-2, 6-3 victory for Jan Choinski and a lesson in composure and resolve for Tiafoe, who’ll return to the courts Monday afternoon for a doubles match with fellow American Michael Mmoh.

Tiafoe, who learned the game at College Park’s Junior Tennis Champions Center, where his father worked as a maintenance man, broke Choinski’s booming serve in the opening game of the match and went on to claim the first set.

But as the match wore on, Tiafoe’s frustration became apparent under the barrage of serves and forehand blasts from the strapping German.

What typically sets Tiafoe apart from other juniors is his on-court composure, his ability to bounce back from a poor shot or poor game and his even-keeled comportment.

All of that deteriorated in the second set and into the third, as Tiafoe shrugged his shoulders, looked repeatedly to his co-coaches in bewilderment and self-loathing and yelled, “SO bad!” after yet another forehand missed its mark.

The junior Grand Slams are open to the world’s top-ranked boys who are 18 or under, which means Tiafoe will have at least two more chances to win the title. After his doubles campaign ends here, he’ll return to College Park to prepare for Junior Wimbledon, which gets under way later this month.

Francis Tiafoe literally grew up around tennis, often spending nights at a Maryland tennis center where his father worked. At only 16, he is ranked number two in the world. Could a future U.S. champion be in the making? (Lee Powell/The Washington Post)