How I loathe sports metaphors. see
https://xkcd.com/904/
Saturday is not a must win. If we lose Saturday, we still have a chance to win Monday. That's the beauty of building a 3-1 lead.
There is no such thing as momentum between games. Most evidently, Calgary had won Gms 3 and 4 very convincingly, and were convincingly pounded in Gm 5.