The Elias Sports Bureau, the NFL's statisticians, deducted the yard Mendenhall was given on a 9-yard run to the Jets 26 in the second quarter.
There was confusion when the chain crew accidentally began moving the yard markers, so referee Peter Morelli's crew placed the ball at the 25 and signaled a first down.
The Steelers' statisticians then credited Mendenhall with a 10-yard run. Elias changed it to a 9-yard gain and tacked the phantom yard onto a sack of Ben Roethlisberger on the following play.
Mendenhall finished with 99 yards on 17 carries, his second 99-yard game this season.