The Spanish teen rocketed to stardom as the youngest man to reach the quarter-final at Flushing Meadows last year and looks on track for another memorable run after making 46 winners to just 10 from his opponent inside Arthur Ashe Stadium.
"I played really, really well," Alcaraz said in an on-court interview. "I knew that it was going to be a tough match... I'm really happy with my performance."
The third seed has enjoyed a terrific 2022, winning in Miami and Barcelona before downing a fearsome trio of Rafa Nadal, Novak Djokovic and Alexander Zverev to win Madrid.
A crisis of confidence led to an early exit from Montreal but Alcaraz showed no such issues on Saturday when he recovered from a slow start in the third set.
Up a break in the second game, Brooksby gave the home crowd a thrill when he fell backwards during a 17-shot rally but incredibly recovered to win the point. He added to the crowd's elation when he broke the third seed to love in the next game.
The party would be short-lived, however, as Alcaraz won the next six games in ruthless fashion.
