Bobby Lynch, Nathan Todd and Joona Luoto scored for Manitoba.
Tyler Graovac added an empty netter to seal the win for the Moose.
Hudson Elynuik and Adam Brooks replied for the Marlies.
Mikhail Berdin made 43 saves as the Moose moved to 1-2-0.
Andrew D'Agostini stopped 15 shots as the Marlies dropped to 2-1-0.
The two teams wrap up their four game series Friday afternoon in Winnipeg.
SHOTS-TORONTO 45 MANITOBA 18