The Milwaukee Journal-Sentinel’s Greg A. Bedard describes the injury:

RB Ryan Grant was wearing a boot on his right foot and has a pretty good sprain. Could not have gone back in.

We won’t know the extent of the injury until later today or tomorrow, but we do know that Brandon Jackson looked pretty good as Grant’s replacement, rushing for 63 yards on 18 tough carries and catching two passes for 12 yards. The yards-per-carry (3.5) numbers aren’t the best, but they don’t tell the whole story. The Eagles defense came to play and the Packers leaned on the former second round pick in both the running game and the passing game to pick up key first downs.

If Grant is on the shelf for any length of time, Jackson will become a RB2-caliber fantasy back, especially in PPR leagues where his pass-catching ability will maximize his value.

Afternoon Update: Grant has already been ruled out for Week 2. Jackson will likely be the top WW pickup of the week.