For the second straight week, Mack and Robinson sat out Wednesday and Thursday before returning to practice on Friday. Both players missed last Sunday's win over the Jets.
"Being sidelined is probably the worst thing in sports," Robinson said Friday. "This is what you love. This is what you live to do. When you're not able to do that, it's definitely frustrating."
Robinson missed the final 15 games last year after tearing his ACL in the season opener while playing for the Jaguars. But last Sunday's experience was a new one for Mack, who sat out a regular-season game for the first time in his five-year NFL career.
"It felt different," Mack said Friday. "I felt like a coach. I just wanted to do what I could as far as helping guys understand what was going to happen early and get the best feedback I could and be a great teammate. It was a real uneasy feeling being [on the sideline], but at the same time I'm glad we got the win. Those guys did a heck of a job. Our defense looked real good."
The Bears aren't expected to announce whether Mack and/or Robinson will play Sunday in Buffalo until the inactive lists are released 90 minutes before kickoff. Asked specifically about Mack, Nagy said: "I feel like we're getting close, I just don't know exactly. That's why we're at that day-to-day deal and hopefully it's continuing to get better each day."
In other injury news, guard Kyle Long (foot) and tight end Ben Braunecker (concussion) were ruled out of Sunday's game, while rookie defensive tackle Bilal Nichols (knee) was listed as questionable after missing practice Friday for the second straight day.
Asked about Nichols, Nagy said: "We're trying to stay positive with it, but it's one of those deals where we've just got to keep an eye on it and see exactly where he's at on the next two days here as we go, see where he's at."