Coach Matt Nagy said Wednesday the three-time Pro Bowl lineman has a boot on his foot and is "week-to-week." The Bears are still trying to figure out the "complete extent" of the injury.
Asked if Long has any broken bones, Nagy said, "I'm not going to get into the details of it." But he added that there are "some issues" with a tendon.
The Bears could place Long on IR with the intent to return in eight weeks if they don't think he could be back sooner.
"Those are decisions we're going through," Nagy said. "We're not there yet. We don't need to be. Once we get to that point, then we'll decide what we want to do."
The injury to Long leaves the NFC North-leading Bears (4-3) in a painful and familiar spot with him as they get ready to visit the Buffalo Bills (2-6). Chicago also could be without star pass-rusher Khalil Mack (right ankle) and No. 1 receiver Allen Robinson (groin) again. The two missed the win over the Jets.
The 29-year-old Long made the Pro Bowl his first three seasons after being drafted in the first round in 2013. But he missed eight games in 2016 and six last season, after playing in 47 of a possible 48 from 2013 to 2015.
Nagy again said the latest injury was not the same as the severe one to his right ankle in 2016 that required surgery. Long also had operations on his shoulder, elbow and neck after he was shut down last year.
"It's tough to hear news like that -- one of our brothers and other family going down," quarterback Mitchell Trubisky said. "We're going to support him all the way and back him up, and then it's next-man-up mentality. We've got a lot of depth at the O-line. I feel really comfortable with where we're at and who's stepping in there."
The Bears could move Eric Kush or rookie James Daniels from left guard, where they have shared time. Kush missed the game against the Jets because of a neck injury, but he is expected to play against Buffalo.
One scenario that apparently can be ruled out is moving Cody Whitehair from center to guard, a position he has played. Nagy said the Bears haven't considered that.
"It's tough to see [Long] go down with the passion that he plays with," Whitehair said. "We hope for the best for him. I know we've got the right guys that will step in for him and give their best."
With Long out, the line loses not only one of its best blockers, but a team leader.
"He helps me a lot with technique stuff," Daniels said. "He also [tells me] if there's a certain look, just be alert for things like that. Both ways, it's nice to have him around."
Game notes: Nagy said the Bears will take a similar approach this week with Mack and Robinson, after both were held out of practice last week on Wednesday and Thursday and limited on Friday.