San Francisco was down at home by 28 to the Saints in 1980....
came back to win by 3 points
Biggest NFL comeback ever (at the time): In 1980, the 49ers trailed New Orleans 35-7 at halftime. The Saints had 20 first downs at the half, the 49ers two. The Saints were 0-13 at the time. Montana drove the 49ers to four second-half touchdowns, and they won in overtime 38-35.