Andrew Kennaugh's surprise run in the French Open boys' singles came to an abrupt end with a 6-0 6-0 defeat to American Sam Querrey.
The 17-year-old Briton, ranked 91st in the junior rankings, came through qualifying to play in a Grand Slam tournament for the first time.
But he was outclassed by world number 18 Querry in the last 16.
Top seed Andrew Murray, Britain's only remaining representative, plays his quarter-final on Thursday.
His opponent is sixth-seeded Argentine Juan Martin del Potro.