"He wanted to continue," said Berhalter about Pulisic after the match. "You could see the disappointment in his face, and we had to make that decision. We made the decision based on being not sure how much he had left. We wanted to inject some energy into the team."
The U.S. midfielder was visibly annoyed after being removed from the game for Paul Arriola at the hour mark. Television cameras showed the Chelsea winger telling Berhalter "I'm fine" before becoming visibly emotional while seated on the substitutes' bench.
Pulisic had struggled for most of the night, but it was still a surprise when he was substituted.
Nine minutes before his removal, he had missed a glorious chance to put the U.S. ahead, after good work from Jordan Morris, scuffing a weak shot directly at Canada goalkeeper Milan Borjan from just 10 yards away.
The early exit was the latest incident in what has been a disappointing few months for the former Borussia Dortmund star.
The 21-year-old midfielder has been mostly a spectator in his first season in the Premier League, limited to two appearances since August: a League Cup start against fourth-tier Grimsby Town on Sept. 25 and a 10-minute substitute stint versus Southampton in the Premier League on Sunday during which he contributed an assist.
Pulisic joined Chelsea from Dortmund in the summer for $73 million -- a record fee for an American player.
Information from The Associated Press was used in this report.