But the good news is the Packers aren't in the same predicament as last year should Clifton be unavailable.
First-round draft pick Bryan Bulaga took over for Clifton midway through the second quarter on Sunday against Buffalo and by all accounts played well. Head Coach Mike McCarthy said Clifton simply didn't look healthy, and he felt it was best to get him out of the game rather than see his play compromised by the balky knee.
"I thought it was affecting the way he was playing," McCarthy said.
Last year the pass protection clearly suffered when Clifton was out with an early-season ankle injury. The coaching staff tried moving Daryn Colledge over from left guard and then later inserting rookie T.J. Lang at left tackle despite limited training-camp reps at that spot. The struggles there, combined with the up-and-down play of Allen Barbre at right tackle, created major pass-protection issues.
On Sunday, the transition to Bulaga was "better" this time, according to offensive coordinator Joe Philbin, though he noted the impressive rookie from Iowa is nowhere near a polished pro.
"I think he graded out fine," Philbin said. "But the more important thing is the film and how it looks. Is he using the techniques and fundamentals you teach on a daily basis? He's got a long ways to go obviously, but for his first time, he did well."
If Bulaga is called upon again this week and can continue to play like he did Sunday, the Packers may be able to afford to give Clifton ample time to rest and heal up. The Packers didn't allow any sacks against the Bills, either before or after Clifton left the game, and Bulaga's lone noticeable hiccup was a false-start penalty.
McCarthy said the medical staff isn't sure if Clifton will be ready to practice on Thursday, the first day of on-field work in preparation for Monday night. Last week, Clifton sat out the first two days of practice in pads and then worked during the final non-padded practice of the week, but it didn't take long in the game for the knee to begin bothering him.
"We need to get him healthy," McCarthy said. "We have a lot of history with Chad. The medical staff has a lot of history with Chad, and when we get him to the point where we feel he's ready to go, he'll go. He's our starting left tackle. He's battling through a rough spot right now medically."
With a Monday night game coming up, the extra day will work in the Packers' favor to give Clifton a chance to be ready, and also to give Bulaga more time to prepare for what could be his first NFL start. That will catch up to both players with the short week following, but that only underscores how important it is for the offense to have two options at that position, given the situation right now.
"I'm sure Bryan will take a lot of the practice reps this week," McCarthy said. "We'll make sure Bryan's ready, and we'll do what we need to do to get Chad ready."
More on injuries
McCarthy indicated linebacker Brad Jones (knee) and safety Nick Collins (hip flexor) should both be fine for the Chicago game, but both could miss some practice time or be limited during the week.
He is hopeful defensive end Mike Neal (side/rib) will be able to return, though that is not certain. Neal has missed the season's first two games. More information is needed on linebacker Desmond Bishop (hamstring) and fullback Korey Hall (hip) before their status for this week can be determined.
The knee injury reported to nose tackle B.J. Raji from Sunday's game doesn't appear to be an issue.
Sharing the load, a different way
In Grant's absence, the three-way split of offensive rushes broke down this way: 11 for Brandon Jackson, nine for John Kuhn, and two for newcomer Dimitri Nance.
That's quite different from the past couple of years, when the No. 1 back, Grant, carried the ball on 83 percent (2008) and 75 percent ('09) of the non-quarterback runs.
But McCarthy explained on Monday that the breakdown is different because Jackson isn't simply assuming Grant's role, which was as a first- and second-down back. Jackson is still keeping some of his third-down responsibilities, so that dictates he share some of the first and second downs with the other backs.
Put another way, Jackson is probably going to play just as many total snaps as Grant did, but he's not going to get as many carries because he's still going to be a pass protector and receiver out of the backfield on third downs, a role Grant didn't play.
"It's a long season," McCarthy said. "We're not trying to play one running back 55, 60 plays in the game and have the other two or three sit on the sideline. We've never played that way."
Regardless of how the carries are distributed, the Packers are looking for better performance in the ground game. Jackson, Kuhn and Nance combined for just 71 yards, or 3.2 yards per rush, against Buffalo. Philbin said there was plenty of blame to go around at different times, between the blocking of the linemen, tight ends and fullbacks, and the decisions of the running backs, and that's of greater concern to him than who's getting how many carries.
"I think we'd all like to see someone get smokin' hot back there and get more than the other guy, but that's still to be determined," Philbin said.
"As a staff we weren't jumping up and down about our run-game production yesterday. We didn't think it was just the offensive line or it was just Brandon or John. There were shots (on the film), like there typically is, that every area could have done a better job. We're kind of working through that."
McCarthy admitted his first-quarter challenge of an incomplete pass to James Jones along the sideline was the wrong decision. The play came on second-and-10 from the Buffalo 20, and Jones leaped high to catch Aaron Rodgers' throw inside the 10, but one foot was right along the boundary.
Rodgers was lobbying McCarthy to throw the challenge flag, and McCarthy said he was hearing from the coaches' booth upstairs that Jones was out of bounds. He challenged it anyway and lost. Even though he said he was going to take a timeout anyway, so he didn't necessarily "lose" a timeout, he did cost himself the possibility of a third challenge should he use his second one later in the game (a team is awarded a third challenge only if both of the allotted challenges result in reversed decisions).
"It was a poor challenge, I shouldn't have challenged it," McCarthy said. "My intent was just to take the timeout. We were down to six seconds on the 40-second clock when I made the decision. I should have taken a timeout there."
The coaching staff awarded game balls to players in the team meeting on Monday. The offensive game ball went to tight end Jermichael Finley, who had four receptions for 103 yards. The defensive game ball went to linebacker Clay Matthews, who had his second straight three-sack game. The special teams game ball went to tight end Tom Crabtree, who had two solo tackles on the kickoff coverage unit. And the "big hit" award went to receiver Brett Swain.