PHILADELPHIA (973espn.com) - Much like the power at the NovaCare Complex on Friday, Zach Ertz and Leodis McKelvin, are out when it comes to Monday night and the Chicago Bears.

The two starters were officially ruled out Saturday morning by head coach Doug Pederson, who had labeled each “week-to-week.”

In the case of Ertz, his absence is hardly a surprise after the tight end suffered a displaced first rib against Cleveland last Sunday with an NFL source telling 973espn.com that the former Stanford star will likely be on the shelf until Oct. 9 in Detroit, after the team’s early bye week.

McKelvin, who is dealing with a hamstring issue that the corner described as a fast-guy injury, was somewhat optimistic when talking on Thursday and defensive coordinator Jim Schwartz intimated his status might be a game-time decision a day later.

Trey Burton, the special-teams ace who was supposed to take on a bigger role in this offense anyway but was a late scratch against Cleveland due to a calf injury, should see plenty of action with Ertz on the sideline.

“Trey’s got to step up, offensive coordinator Frank Reich said Friday. “We've got to adapt. You just switch up your personnel groups. The good thing is, with this offensive system, it’s all built on a multiple approach. You can change formations. You can change personnel groups and still run the same plays.”

As for McKelvin, both Ron Brooks and rookie Jalen Mills will be counted on to help alleviate his loss.

According to Mills, he was still working with the second team in practice on Friday, indicating Brooks may move from his slot position to the outside in the base defense and then return inside with Mills entering when the team goes into the nickel.

Pederson confirmed that's the plan on Saturday.

"In our base defense, Brooks will start. Jalen will come in in nickel and dime situations," the coach said.

Schwartz could have started the seventh-round pick on the outside and kept Brooks in his more familiar spot but is likely wary of putting too much on Mills' plate right away.

The rookie played well in 12 snaps against the Browns after McKelvin went down with the injury. Brooks, on the other hand, handled the slot duties, playing in 73 percent of the defensive snaps and registering a tackle and a pass defended.

Mills does offer a bit more length, however, which could be important against Chicago’s king-sized receivers, Alshon Jeffery and Kevin White.

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen