The Packers aren't expected to run the ball that much against the Vikings' run defense anyway, but an injury to a running back may prompt even more use out of Brett Favre's arm.
The Packers apparently will have a new starter at halfback when they play at Minnesota on Sunday.
Rookie Brandon Jackson
, who had little production as the featured back the first three games, was out of practice Thursday because of a strained left shin.
Jackson suffered the injury in last Sunday's win over San Diego and dropped out of practice Wednesday.
His status for the upcoming game is iffy at best. Head coach Mike McCarthy wasn't certain after practice Thursday that Jackson would be on the field Friday.
The timing of Jackson's setback coincides with positive strides made by Vernand Morency
in practice this week.
Morency might have finally turned the corner with lingering knee soreness that kept him out of game action so far.
"He looked good two days in a row," McCarthy said. "He's put together back-to-back practices, where in the past he's been frustrated the day after a hard practice because of the way he feels."
Morency was the projected starter at halfback entering the preseason but suffered a sprained patellar tendon in his right knee on the first day of training camp.
The Packers have primarily relied on Jackson and fellow rookie DeShawn Wynn
in Morency's absence and managed to start the season 3-0 despite having the league's worst rushing attack. Green Bay is averaging 57 yards per game on the ground and faces a stern challenge against the Vikings, who are yielding a per-game rushing average of only 67.3 yards to rank third in the league.
McCarthy, who resorted to a pass-run ratio of 70-30 through three games, is determined to get the running game on track Sunday.
"You need to run the football, especially on the road," he said. "It's a part of what we do, and it's important for us to do it this week."
WR Greg Jennings was held out of practice Thursday as a precautionary reason. Jennings had limited work the previous day. The additional rest is intended to preserve Jennings for game day after he missed the first two games because of a pulled hamstring. Jennings should practice Friday and be ready to make the start against the Vikings on Sunday.
QB Brett Favre had full participation in practice after he was limited Wednesday because of a small cut on a finger of his throwing hand. Favre is set to make his 241st straight regular-season start, which would move him ahead of former Minnesota center Mick Tinglehoff for second place on the NFL's all-time list for starting streaks.
WR Donald Driver also went through the full practice Thursday and will be ready for Sunday despite coming out of the last game with a toe injury.
DE Cullen Jenkins was held out of most drills for the second straight day as he tries to bounce back from a rib injury he sustained in the previous game. If Jenkins isn't cleared for Sunday, Corey Williams probably will slide outside and start at right end.
CB Al Harris, beset by back spasms the last two games, was limited Thursday but figures to go through the full practice Friday and make the start Sunday.
CB Charles Woodson has been held back the last couple days because of lingering hip and foot injuries but expects to go through the full practice Friday and start Sunday.
TE Bubba Franks returned to practice, albeit on a limited basis, after being out Wednesday. He aggravated a knee injury in the last game and was given extra time for recovery. He'll likely be ready for Sunday.
LT Chad Clifton has been limited the past two days because of lingering knee soreness, though he's expected to make the start Sunday.