PHILADELPHIA (973espn.com) - Struggling Eagles cornerback Ronald Darby could miss up to a month of action with a hamstring injury.

NFL Media first reported the severity of the injury after an MRI Monday. Darby was forced out of the 27-23 loss to Detroit last Sunday at Lincoln Financial Field.

Regarded as a deep position entering training camp that's all changed in the ensuing weeks because Jalen Mills has been slow to recover from foot surgery and is on the physically unable to perform list and Cre’Von LeBlanc was placed on injured reserve with his own foot problem.

That means the Eagles are down to three healthy cornerbacks -- Rasul Douglas, Sidney Jones and Avonte Maddox -- on a short week as they prepare to visit Aaron Rodgers and the Green Bay Packers on Thursday night. Douglas and Jones are expected to start outside against the Packers with Jones replacing Darby at left corner while Maddox will continue to work in the slot as the nickel corner.

Philadelphia is also likely to promote Craig James from the practice squad in time for the game. James and tight end Alex Ellis have been ping-ponging back and forth from the PS to the active roster with the former dressing in Atlanta during Week 2.

Darby, meanwhile, has been struggling mightily in his return from a torn ACL and it certainly seems like the opposition has been targeting the Florida State product, who may not feel fully confident in the knee he hurt last November.

Darby's has been marred by injuries since being acquired from Buffalo before the 2017 season. He dislocated his ankle in the season opener that season and tore the ACL in Week 10 last season.

Rookie receiver J.J. Arcega-Whiteside was the other notable addition to the Eagles' Monday injury report which was an estimation because the practice was a walkthrough.

There was some good news as well as receiver Alshon Jeffery was estimated as a limited participant as he tries to return from a calf injury while linebacker Kamu Grugier-Hill was listed as a full participant and is expected to play Thursday after missing the first three games with an MCL sprain suffered in training camp.

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