Newaygo netted the lone first half goal to take a 1-0 lead into halftime.
In the second half, Newago netted a second goal to take a 2-0 lead.
However, the Wildcats responded with a Pablo Alfonso Viguria goal off an assist from Carter Mahoney to cut the deficit to 2-1.
Later in the half, Brenden Mahoney netted a penalty kick to tie the game at 2-2.
With just two minutes left in regulation, Kevin Roll netted the game winning goal for Montague.
Montague will next face Oakridge in the Division 3 district semifinals at Oakridge on Tuesday at 7 p.m.