Yantz threw for 361 yards and two touchdowns for Manitoba while also rushing three times for 33 yards.
Nic Demski caught eight passes for 155 yards and one touchdown for the Bisons. Demski also threw the late touchdown in the fourth quarter to help secure the win.
Drew Burko made 29 completions, throwing for 402 yards and two touchdowns for Saskatchewan in the loss.
Manitoba will now face either Regina or Calgary in the Hardy Cup on Nov. 15.