Jackson, a freshman who leads the Western Athletic Conference in rushing, suffered a high ankle sprain against Northern Illinois last weekend.

Jackson has gained 537 yards on 100 carries in Idaho's first four games.

Idaho's training staff will use "aggressive treatment" on Jackson's ankle, coach Robb Akey said.

"If that progresses well later in the week, then the opportunity to play him might be there," Akey said. "But I don't know that it's realistic thinking that I'm going to have him available this weekend."

If Jackson is out, veteran Jayson Bird will get more carries.

"I feel very comfortable with the pressure on my shoulders," said Bird, a junior from Shelley. "I hope I showed a little bit of it last week."

Bird had just 10 carries in Idaho's first three games, but got more action last Saturday when Jackson was hurt in the third quarter. Bird ran eight times for 52 yards and caught five passes for 72 yards.

Bird, who led Idaho in rushing as a freshman in 2004, has 1,536 career yards.

Idaho is also hoping to have Brian Flowers back from a hamstring injury. The senior practiced Tuesday, but Akey said his availability will probably be a game-time decision.