Overmatched at Dallas on Saturday,the Rams' starters likely will play into the third quarter Thursday night against Baltimore.

Starting RB Steven Jackson will get some touches but isn’t expected to be on the field the whole time with that group. He did not get a carry against the Cowboy, instead being used in pass protection.

Rookie RBs Isaiah Pead and Daryl Richardson should get a shot to play with starters as they keep battling for the No. 2 job. Coach Jeff Fisher told the Rams’ official website that several factors will determine the gameday depth chart, including the special teams roles the backups hold.

Pead has averaged 31.0 yards on four kickoff returns. Richardson has run more decisively. Against the Cowboys, Richardson gained 51 yards on 10 carries and caught a nine-yard pass.

Fisher, who indicated starters likely will play one series after halftime, all along had planned to give them the most work in the final preseason game. He believes in steadily increasing their workload, as opposed to using the third game as the dress rehearsal.

O-line concerns: Fisher told the Post-Dispatch he’s not overly worried that the starting offensive line hasn’t had time to jell. Center Scott Wells missed the first two preseason games rehabbing from knee surgery, and guard Harvey Dahl missed the third with an infection. Dahl is not expected to play Thursday.

"It's important, but (Wells and Dahl) have a great deal of experience," Fisher told the paper, "and the time that they have had in there, they've worked well together. … Scott's going to play a little bit more (on Thursday), Harvey probably won't play. But Harvey has plenty of experience right now, so we're OK.”

Fisher noted the veterans’ absences enabled Bryan Mattison, Robert Turner, Quinn Ojinnaka and Rokevious Watkins to get “extremely valuable reps, live reps, game reps.”

Stewart still out: S Darian Stewart (hamstring) was held out of Tuesday’s practice and is unlikely to play Thursday. Craig Dahl should start at free safety and appears certain to start the season opener.

Defensive end Eugene Sims (ankle) and defensive tackle Darrell Scott (knee) also remain out.

Get more Rams updates and analysis from Larry Hartstein @CBSSportsNFLSTL.