"Running back Ryan Grant will miss the Green Bay Packers' home opener Sunday against Buffalo with an injured ankle. After that, his status remains unknown.

During his news conference Monday morning, coach Mike McCarthy said Grant was still taking tests and waiting for results to determine the severity of the injury that was, the day before, described as a sprain but now appears more severe.

"It's a significant injury to the ankle and the ligament involved in the ankle," McCarthy said.

McCarthy also said he didn't yet know if the injury would require surgery.

Grant was not available in the locker room, but he spoke to 1250 WSSP radio later Monday. Grant was vague about the injury, saying only that he would take it week to week.

McCarthy doesn't plan to make a decision about a potential roster move - like possibly promoting James Johnson from the practice squad or signing a free agent - until he knows the full extent of Grant's injury.

There aren't many quality options available to the Packers if they choose to sign a free agent. The most noteworthy would be former Pittsburgh Steeler Willie Parker, who was released by Washington at the end of training camp. A few other veterans out of work are Ahman Green, Justin Fargas, J.J. Arrington, Adrian Peterson (not the Viking) and Kolby Smith.

In a pinch, the Packers also could consider activating Johnson from the practice squad, though the free agent has been with the Packers for just a week.

"He's coming along," said running backs coach Edgar Bennett. "He's getting better day in and day out and he's come along at a pretty rapid pace."

The Packers can probably get away with Brandon Jackson and John Kuhn for a game or two, but if it's longer than that, the Packers will have to make a move. The Packers have a roster spot available because they also placed Justin Harrell on injured reserve Monday after he hurt his knee.

Grant left the game with 45 yards and was just starting to find holes when he was injured in the second quarter.

"As far as pressing his aiming point and things like that, certainly he started getting into a rhythm," said Bennett. "He was seeing it. Obviously it's unfortunate for Ryan."

The injury leaves the Packers thin at the position, since they kept just two running backs on the roster, Grant and Jackson. Jackson had 18 carries for 63 yards in Philadelphia on Sunday.

One of the three fullbacks, Kuhn, also can play running back. He was instrumental in one Green Bay scoring drive Sunday when he ran for 12 yards, dragging tacklers with him, and then scored on a 3-yard burst in the third quarter."