Grant suffered the injury to his right ankle before halftime of the Packers' 27-20 win at Philadelphia Sunday. Brandon Jackson replaced Grant in the backfield.
Green Bay Coach Mike McCarthy said Grant will be out for the Packers' game Sunday against the Buffalo Bills. The team should have a better idea on when Grant might return after further testing.
"It's a significant injury to the ankle and the ligament involved in the ankle, which has now required more testing, and we'll continue to process all the information throughout the day," McCarthy said Monday.
Grant rushed eight times for 45 yards before the injury. He ran for more than 1,200 yards each of the last two seasons and was third in the conference in 2009 with 1,253 yards.