Lacy couldn't finish Sunday's loss at the Carolina Panthers because of the injury, adding to what has already been an unproductive season for him.
Lacy, the 2013 NFL offensive rookie of the year, dropped out late in the third quarter of Sunday's 37-29 loss to Carolina Panthers and did not return. The severity of Lacy's injury was not known.
It's the second injury Lacy has suffered this season. He sprained his right ankle in Week 2 against the Seattle Seahawks, and although he did not miss any games, his production has been on a sharp decline.
Lacy rushed for only 10 yards on five carries against the Panthers and hasn't had more than 38 yards in any of his last four games. His playing time has been significantly reduced since James Starks rushed for 112 yards on 10 carries against the Chargers on Oct. 18, when Lacy carried only four times for 3 yards.
Even before the injury on Sunday, Lacy was benched for three series after losing a fumble in the second quarter.
After consecutive 1,100-yard rushing seasons in his first two years in the NFL, Lacy has just 308 yards at the midway point of the season. Starks leads the Packers with 334 rushing yards this season. He rushed for 39 yards on 10 carries and also caught six passes for 83 yards and a touchdown Sunday.
The only other injury the Packers announced was to cornerback Casey Hayward, who left the game to be evaluated for a concussion.