Brandon Jacobs ran right and was cut down short of the marker, forcing a turnover on downs by the Giants.
The Giants have struggled early against the stingy 49ers defense that was one of the NFL's best in 2011. Eli Manning has six completions for 46 yards, but none for more than 12 yards, and Ahmad Bradshaw has just 16 yards on six carries.
To make matters worse, Hakeem Nicks left the field on the drive with a shoulder injury, though his return is probable.
For updates and analysis on these teams throughout the 2012 NFC Championship Game, visit 49ers blog Niners Nation, Giants blog Big Blue View and SB Nation New York and SB Nation Bay Area. Don't forget to check out SB Nation's NFL hub for all your playoff news.