Khalil Mack (right ankle) and Allen Robinson (groin), the Bears' best player and No. 1 receiver, respectively, practiced in full Wednesday following two-game injury absences. Neither practiced the previous two Wednesdays and Thursdays before being limited Friday and deactivated vs. the Jets and against the Bills.

The Bears also welcomed back rookie fifth-round DL Bilal Nichols, who practiced in full after missing Sunday with a knee injury he sustained in practice last week. Co-starting LG Eric Kush and backup TE Ben Braunecker were also full participants, while WR Taylor Gabriel (knee) was limited and TE Dion Sims (concussion) was out.

And second-year TE Adam Shaheen, who's been on injured reserve with a right foot/ankle injury since the preseason, practiced for the first time, as the Bears started the clock on a three-week window in which he can be activated.

In other words, the first-place Bears are getting significant reinforcements ahead of their most critical stretch of the season, including three divisional games in 11 days, beginning with the Detroit Lions coming to town Sunday.

We've already seen the impact Mack, Robinson and Nichols are capable of making.

Mack, the NFL's Defensive Player of the Month in September, injured his right ankle early on in Miami and battled, albeit ineffectively, through it in losses to the Dolphins and Patriots — Chicago's two worst defensive performances — prior to missing the past two games. If he were to return Sunday, Mack would draw Lions RT Rick Wagner, who just allowed Vikings LDE Everson Griffen to claim Defensive Player of the Week honors after tallying 3.5 of Minnesota's franchise-record 10 sacks Sunday.

Robinson was Mitch Trubisky's favorite weapon in the first five games, tallying 24 catches for 281 yards and two touchdowns prior to injuring his groin vs. the Patriots. Chicago has showed off its improved WR depth in Robinson's absence but doesn't have another big-bodied wideout with his rounded game.

Nichols seemingly came out of nowhere after being a healthy scratch in Week 1 to tally three tackles for loss, a forced fumble and fumble recovery between Weeks 3-7. Roy Robertson-Harris was outstanding in Buffalo after reclaiming some of the snaps he'd lost to the rookie.

Second-year TE Adam Shaheen, though, has been out of commission since planting his right foot awkwardly into the ground on Aug. 9 in the preseason game in Cincinnati. It was especially unfortunate because he was having a terrific camp and appeared on his way to carving out a major role on offense as the team's No. 1 'Y' tight end and most imposing red zone threat.

"We’re looking forward to Adam being back," Mitch Trubisky said Wednesday of Shaheen, who could return as soon as Sunday. "Me and Adam have a great connection from last year; obviously a big target and runs good routes for his size and can separate.

"He’s just a mismatch problem across the board for linebackers and safeties, and when you get a corner on him as well, his size is just too much to handle. Getting him back will just open things up even more for this offense and he’s another option for this offense to be even more dynamic.”

Chicago has exceeded most expectations so far on offense, especially considering it's a new scheme with mostly brand-new artillery and a quarterback with minimal starting experience. The Bears rank No. 9 in the red zone and No. 11 on third down — two areas where Shaheen figures to be especially helpful — but they've converted only 7-of-23 third-down chances over the past two games.

"He was still digesting the playbook, but you saw some things that he was doing," Matt Nagy said of Shaheen's progress this summer prior to his injury. "He was getting the ball a little bit, and he's a nice-sized guy, so one-on-one battles he does well with. But he was also learning how to play tight end and how to run some of the routes that we run in this offense, so it was tough to see him go down the way that he did because I thought that he was — really, he was one of those guys that was progressing pretty fast. So, it'll be exciting to get him back out there and see exactly where he's at."