Conversation so far:
Did Steve Young play any notable games while a backup?
Substituting for an injured Montana, early in the first quarter of a 1987 game against the Chicago Bears, he threw four touchdown passes in a 41-0.
Did they win that game?
41-0 victory.
Did he play any other notable games?
he replaced Montana in the second half after the team fell behind 27-10.
The 49ers still lost the game, but Young had a fairly good performance.
Who were the 49ers playing in this game?
Minnesota Vikings.

Question: When was this game being played?
Self-contained rewrite: When was the Minnesota Vikings game against Montana being played?