The Washington Redskins plan to turn to Jarvis Jenkins and either Rob Jackson or Chris Wilson as starters this week after losing a significant portion of their pass rush to season-ending injuries suffered by defensive end Adam Carriker and outside linebacker Brian Orakpo Sunday.

Little has gone as planned for the unit, which had visions of becoming one of the league’s top defenses this year, but finds itself near the bottom ranks of the NFL. Now the Redskins could be without as many as four starters on defense for Sunday’s meeting with the Cincinnati Bengals at FedEx Field, and replacing Carriker and Orakpo will be a season-long task.

The Redskins say they’re confident that their fill-in starters will be up to the task.

“Backups such as myself and Jarvis, I think we’ve got the talent and capability of filling in and doing more than just doing our job, actually going out there and making plays,” Jackson said.

Ryan Kerrigan, the team’s other starter at outside linebacker, said: “You look at Rob Jackson coming in and playing for ‘Rak [Sunday]. He played really well. And then Jarvis and Kedric [Golston] coming in for Adam—we’ve got guys that can step in and fill their shoes.”

Sunday’s loss in St. Louis was a calamitous outing for the defense. The Rams amassed 452 yards on offense in their 31-28 triumph. Quarterback Sam Bradford threw for 310 yards and three touchdowns. Wide receiver Danny Amendola had 15 catches. The Rams overcame a 21-6, second-quarter deficit and the Redskins failed to compensate for the exits of Carriker, who suffered a torn quadriceps tendon near his right knee, and Orakpo, who left with a torn left pectoral muscle.

“I feel like we gave one away,” Jackson said. “I felt like we had a lot of opportunities to win the game or take it to overtime…. I felt like defensively we gave them a lot of yards and we were out of position. I’m just happy it’s the second game of the season and we can come back next week and regroup and fix the little things that we did wrong.”

The Redskins plan to look at Jackson and Wilson during practice this week before choosing a starter for Orakpo’s outside linebacker spot for Sunday’s game against the Bengals. The two could split time at the position.

Jenkins, a second-round draft pick last year who missed all of his rookie season because of a knee injury, takes over for Carriker at left defensive end.

“We’ve got to go back to doing our job and hold everybody accountable,” Jenkins said. “The defensive line has got to get pressure on the quarterback. The corners have got to cover. It’s an 11-person game. We’ve got to go in and do our job and be focused on every play.”

Orakpo, with a team-leading nine sacks last season, and Carriker, with 5-1/2, had more than one-third of the Redskins’ 41 sacks between them last season. More of the pass-rushing burden could fall on Kerrigan, who had 7-1/2 sacks last season as a rookie and has one in two games this season.

“I don’t feel more pressure, but it’s definitely a greater sense of urgency now…. I definitely have to step it up personally,” Kerrigan said.

With Orakpo out of the lineup, the Bengals and future opponents may devise game plans that focus more attention on Kerrigan. The second-year linebacker said he didn’t notice the Rams putting any additional focus on him after Orakpo left the game last weekend.

But that was a small sample, and Orakpo returned to that game twice before leaving for good. So Kerrigan might have to adjust this weekend.

The Redskins are ranked 28th in the league in total defense. Coach Mike Shanahan has said since the team drafted quarterback Robert Griffin III in April that having a strong supporting cast around Griffin would be a key to the season. The Redskins thought the defensive part of that equation would be easiest. They finished last season ranked 13th in total defense and players talked during training camp about moving up this season.

But it has been a struggle through season-opening road games in New Orleans and St. Louis, and merely patching together a lineup will become an issue this week. Safety Brandon Meriweather has missed the first two games because of a knee injury and it’s unclear whether he will be ready to return to the lineup this week. Cornerback Josh Wilson left Sunday’s game with a concussion and must be cleared by an independent neurologist before he practices or plays.

“It’s so frustrating looking back and knowing that we had a 21-6 lead and let it slip away,” Kerrigan said. “Especially defensively, we didn’t do the things we needed to do to win the game. That’s what’s frustrating. But we’ve got to let it go and move on.”