Britain's Andy Murray was overpowered by Felix Auger-Aliassime in the US Open second round, losing 6-2 6-3 6-4 in New York.
Murray, 33, came back from two sets down in his first-round match on Tuesday but never threatened to do the same against the 20-year-old Canadian.
He was not able to create a break point against the 15th seed under the roof on Arthur Ashe Stadium.
Auger-Aliassime will face Britain's Dan Evans or Corentin Moutet next.
The British number one and France's Moutet must finish their second-round match on Friday after heavy rain stopped play on Flushing Meadows' outside courts.