Washington Coach Ron Rivera underwent treatment for cancer Tuesday and was absent from practice as his team began to prepare for Sunday’s season opener against the visiting Philadelphia Eagles.

As planned, defensive coordinator Jack Del Rio led the workout. Afterward, he told reporters that Rivera was expected back Wednesday.

“We got all our plans laid out,” Del Rio said. “We carried on as normal. I tended to the things that needed to be tended to, but it was pretty much business as usual.”

Rivera announced Aug. 20 that he was diagnosed with squamous cell carcinoma in a lymph node in his neck. In subsequent interviews, the most recent of which was recorded last week for the “Huddle and Flow” podcast hosted by Steve Wyche and Jim Trotter — Rivera has said he will have proton therapy and indicated chemotherapy might be involved, too. He will have 35 treatments, spread over nearly two months.

According to Neil Gross, director of clinical research in the department of head and neck surgery at MD Anderson Cancer Center, some patients with squamous cell carcinoma must have the cancerous tissue removed. For others, the cancer can be treated non-surgically with some type of radiation that is usually paired with chemotherapy to enhance its effectiveness.

Proton therapy is a form of radiation that delivers high-energy doses to a targeted area, so it’s believed to cause less collateral damage to nearby healthy tissue than X-ray radiation.

“It’s a pretty intense treatment,” Gross told The Washington Post in August. “While the prognosis is good, it’s a hard treatment for patients, and that’s because the throat is so exquisitely sensitive.”

On the podcast with Wyche and Trotter, Rivera said he underwent procedures before treatment. He didn’t specify what those procedures entailed but said the last one “knocked me down a little bit.”

For patients facing radiation and chemotherapy, Gross said they will typically have a few things done. Among them: a laryngoscopy with biopsy to determine the primary site of the cancer and the treatment area.

“The last procedure, I was prepared for the worst outcome, and that was having to actually have them remove something,” Rivera added. “But fortunately they were able to find what they were looking for and we were able to nip it and now we’re getting ready for the therapy part. It’s not down by the vocal cords, thank goodness. It’s in a spot where it was close enough to the lymph node that that’s where it got into the lymph node. This is not lymphoma. This is cancer that got into the lymph node, and it’s something they’ll be able to take care of through proper therapy and treatment.”

Rivera’s hope was that he could continue coaching, and up until the start of treatment, he was; his procedures were scheduled during players’ off days. But he also acknowledged back in August that he would struggle at times, so he and his staff laid out a Plan B: When he couldn’t lead the team, Del Rio would for him, while also continuing his duties as defensive coordinator.

Del Rio was a head coach in Jacksonville and later Oakland for a total of 12 seasons. In between, he was defensive coordinator in Denver and was its interim coach for four games in 2013, when John Fox underwent heart surgery.

“Having had that experience, I don’t really give it a lot of thought,” Del Rio said. “Coach says he’s going to be out, [and] it means he needs me to step in. I’m like, ‘I got you, Coach.’ Then I’m just going to carry on his message. We’re going to stay on point with what we’re doing. I pay attention to what he’s saying to the staff and what he’s saying to the team and I echo those things. So it’s very much just taking control in a way that he would and making it easier for everyone that we’re working with.”

Del Rio said he learned over the weekend that Rivera would be absent from Tuesday’s practice but that it has been “pretty seamless” in moving forward with game preparation.

“To be honest, it did feel a little weird because of what’s going on, what he’s going through,” cornerback Ronald Darby said. “But we got to keep pushing, and I know he’s going to be good.”

Rivera was absent, but Washington’s first unofficial depth chart arrived Tuesday. As expected, it features Dwayne Haskins as the starting quarterback; Terry McLaurin, Dontrelle Inman and Steven Sims Jr. as the starting wide receivers; and the same offensive line that started for much of training camp: Morgan Moses at right tackle, Brandon Scherff at right guard, Chase Roullier at center, Wes Martin at left guard and Geron Christian Sr. at left tackle.

It was notable, but perhaps not surprising, that Kyle Allen was listed as the backup quarterback and Alex Smith was the third-stringer, an indicator he could be inactive on game days.

More surprising, perhaps, was the order of the running backs. After releasing Adrian Peterson (who has since signed with the Detroit Lions), the team listed J.D. McKissic as its No. 1 back, followed by rookie Antonio Gibson, Peyton Barber and Bryce Love.

During training camp, Rivera said McKissic would be used more on situational downs, and his spot on the depth chart doesn’t necessarily mean otherwise. His versatility — as well as that of Gibson (another converted wide receiver) and Love — gives offensive coordinator Scott Turner multiple options in how he uses his backs.

“Being named the No. 1 running back, that’s new to me. I just know that I’m not going to let it get to my head because I may not even be the first guy to step on the field Sunday,” McKissic said.

On defense, the starting line was the same as the first unit in camp, with rookie Chase Young and Montez Sweat at end and Daron Payne and Jonathan Allen at tackle. At linebacker, Thomas Davis was listed as an outside linebacker but as a second-stringer behind Shaun Dion Hamilton. Jon Bostic is the starter at middle linebacker, and Kevin Pierre-Louis will start at the other outside linebacker position.

Washington’s first depth chart of 2020

OFFENSE

QB: Dwayne Haskins, Kyle Allen, Alex Smith

RB: J.D. McKissic, Antonio Gibson, Peyton Barber, Bryce Love

WR: Terry McLaurin, Antonio Gandy-Golden

LT: Geron Christian Sr., Saahdiq Charles, David Sharpe

LG: Wes Martin, Wes Schweitzer

C: Chase Roullier, Keith Ismael

RG: Brandon Scherff, Wes Schweitzer

RT: Morgan Moses, Cornelius Lucas

TE: Logan Thomas, Jeremy Sprinkle, Marcus Baugh

WR: Steven Sims Jr., Isaiah Wright

WR: Dontrelle Inman

DEFENSE

DE: Chase Young, Ryan Kerrigan

DT: Daron Payne, Tim Settle

NT: Jonathan Allen, Matt Ioannidis

DE: Montez Sweat, Ryan Anderson, James Smith-Williams

OLB: Shaun Dion Hamilton, Thomas Davis

MLB: Jon Bostic, Cole Holcomb

OLB: Kevin Pierre-Louis, Khaleke Hudson

CB: Kendall Fuller, Jimmy Moreland, Danny Johnson

CB: Ronald Darby, Fabian Moreau, Greg Stroman

SS: Landon Collins, Deshazor Everett

FS: Troy Apke, Kamren Curl

SPECIALISTS

P/H: Tress Way

K: Dustin Hopkins

LS: Nick Sundberg

KR: Steven Sims Jr., Antonio Gibson, Danny Johnson

PR: Steven Sims Jr., Isaiah Wright