The Chargers have spent much of the preseason without two of their defensive cornerstones, All-Pro safety Derwin James Jr. and four-time Pro Bowl edge rusher Joey Bosa, but a return is on the horizon for both.

The expectation is that both will be ready for the season opener on Sept. 8 against the Las Vegas Raiders, according to coach Jim Harbaugh.

Although Harbaugh didn’t go into detail about the injuries James and Bosa have been dealing with — offering only his usual “working through something” line — he did mention the training staff expects both to be available to start the season.

Bosa, absent since leaving the joint practice with the Rams on Aug. 4 because of an apparent hand/wrist injury, was working off to the side Thursday during practice.

Chargers safety Derwin James Jr. has watched many practices from the sideline during camp.

(Allen J. Schaben / Los Angeles Times)

Although there was no official update on Bosa’s injury, he had been spotted with a wrap around his left hand and forearm.

James’ situation is more uncertain.

He has been absent from practice for nearly two weeks, in addition to missing several practices throughout training camp. No details of his injury have been provided.

Neither James nor Bosa has suited up for a preseason game, and they are not expected to do so for the preseason finale Saturday against the Dallas Cowboys.