The play occurred just over four minutes into the contest. Blais was handed a two-minute minor for elbowing. Toews was shaken up but remained in the game.
Blais, 24, has no prior history of supplemental discipline over 84 regular-season contests. The 6-foot-2 forward later added an assist in the Blues' 4-1 victory.
The Avalanche acquired Toews from the New York Islanders in October and signed him to a four-year, $16.4-million deal shortly after.
Blais will sit for the first game of his suspension when the Blues take on the Avalanche in a rematch Friday.