Leighton Vander Esch, Blake Jarwin among injured Dallas Cowboys ruled out

Dallas Cowboys linebacker Leighton Vander Esch suffered a fractured collarbone during Sunday's season-opening 20-17 loss to the Rams in Los Angeles, the team confirmed. It was one of three significant injuries that the medical staff will assess further on Monday.

Tight end Blake Jarwin suffered what is feared to be a torn ACL in his right knee, a source confirmed to ESPN's Ed Werder. The Dallas Morning News first reported the nature of Jarwin's injury during the game, and there is an MRI planned this week.

Offensive tackle Cameron Erving left the loss with a left knee injury and will miss time.

Jarwin's injury was described as "possibly a longer-term" injury, a source told ESPN, and quarterback Dak Prescott addressed that potential in his postgame availability.

"I know he's a great asset to this offense," Prescott said. "Would hate to lose him for the rest of the year if that's the case."

Dallas signed Jarwin to a four-year extension with big plans for him under new coach Mike McCarthy after Jason Witten left in free agency for the Raiders. Jarwin reached for his right knee after falling to the ground while running a route in the opening half. That came not long after he caught a 12-yard pass.

Erving appeared to have his knee rolled up on while he was blocking on special teams.

Vander Esch -- replaced by Joe Thomas, who finished with five tackles and a quarterback hurry -- was not credited with a tackle in the loss, and he received a significant amount of time early on. In fact, the Cowboys' defense was on the field for 23 plays in the first quarter, allowing an opening-drive touchdown. The second drive ended with a missed field goal attempt.

Because of a previous neck injury, Vander Esch was playing in his first game since Week 10 last season. He had offseason neck surgery, in fact, but said he felt fine throughout training camp. In a switch for this season, under McCarthy, Vander Esch took over as the middle linebacker, switching positions with Jaylon Smith, and began the night serving as the defensive signal-caller.

"A guy like Leighton, he's a first-round pick for a reason," Smith said. "He has a bunch of capabilities that he can do. ... But we have depth. Joe stepped in and did a good job making plays. I just think collectively as a defense, myself included, we've all got to play better. We have a standard and we have to play up to that."

With Sean Lee on injured reserve and missing the first three games because of a pelvis issue, the Cowboys have veteran Justin March, who is mostly a special-teamer, in reserve, in addition to Thomas at linebacker. Luke Gifford, also a linebacker, was among the team's inactives Sunday, and he is dealing with a hamstring issue.