The league was known as the American Professional Football Association (APFA) during the 1920 and 1921 seasons
BUF 7
CHI 10
Champ
CHI
1921 NFL Champion Chicago Staleys
z: best record, c: conference winner, y: division winner, w: wildcard, x: clinched playoff spot

de facto Championship Game

After a mid-season loss between the two undefeated teams, the All-Americans agreed to rematch the Staleys at the end of the season, on the condition that the game would be considered a "post-season" exhibition game not to be counted in the standings. Going against Buffalo's wishes, the league actually counted the All-Americans game in the standings, resulting in Buffalo (9–1–2) and Chicago (9–1–1) being tied atop the standings. The league then implemented the first ever tiebreaker: a rule, now considered archaic, that stated if two teams played multiple times in a season, the last game between the two teams carried more weight. Thus, the Chicago victory actually counted more in the standings, giving Chicago the championship.
Date    OpponentResultScore
12/4vs BuffaloW  10-7