Conversation so far:
Did anything happen significant in the 1979 NFL season for Dan Dierdorf?
On September 9, 1979, Dan Dierforf sustained torn ligaments in his left knee in the second quarter of the second game of the season against the New York Giants.
Who did Dan Dierdorf play for during the 1979 to 1983 NFL seasons?
Dan Dierdorf played professional football in National Football League with the St. Louis Cardinals for 13 seasons from 1971 to 1983.

Question: He was against the Giants? Who did he play for?
Self-contained rewrite: Dan Dierdorf was against the Giants on September 9, 1979? Who did he play for?