Rookie Andre Dillard is essentially trying to unlearn 10 years of football in a week.

A left tackle since he started playing the game at the age of 14, Dillard took a crash course at right tackle, where he will start for the Eagles Sunday afternoon (1) against the Seahawks. Regular right tackle Lane Johnson was ruled out Friday due to a concussion he suffered in last week’s 17-10 loss to the Patriots.

Asked how much of an adjustment it is after Friday’s practice, Dillard replied, “A big one.” Then he asked the questioner which hand the reporter uses to write with. Informed it was the reporter’s right, Dillard said, “Write with your left hand.”

“It takes a lot of repetition because it’s a big muscle memory thing more than anything,” Dillard said. “Your eyes, your brain, your head — your entire body, really — if you go your whole life doing one thing one way and then you suddenly flip it on a week’s notice, your brain’s kind of like ‘Whoa.’ It doesn’t feel right.”

Pass rushers going outside will now be on Dillard’s right instead of his left. Flip that for inside rushers.

One advantage the left-handed Dillard has is that he can — and does — call upon tackle Halapoulivaati Vaitai, who has played both positions.

“He gives me pointers,” Dillard said. “I can kind of look to him as a guy who’s been through a lot and been through all that swing (tackle) stuff.”

Having All-Pro right guard Brandon Brooks next to him is another big plus. Brooks has mentored the 6-foot-5, 315-pound Dillard since soon after the Eagles made him their first-round pick on April 25.

Brooks is an eight-year NFL veteran who has made 99 of his 100 starts at right guard. He started one game at left guard for the Texans in 2015.

“Just any questions he has, answering them for him,” Brooks said. “Any looks (we see), make sure we’re on the same page. Doing everything I can from that standpoint.

“He’s young, so going from left to right will be a little tough on him. As you get older, you play more both sides.”

Dillard has logged 294 offensive snaps — 288 at left tackle and six as the extra tight end Sunday after Vaitai, who normally handles that role, replaced Johnson at right tackle. Dillard started three games in place of Peters at left tackle and held his own, which is extremely important because of protecting the quarterback’s blind side.

Peters sat out two snaps against New England in the fourth quarter and Dillard replaced him. Peters wasn’t listed Friday’s final injury report but had been limited in practice Wednesday and Thursday because of the knee.

It’d be interesting to see what Doug Pederson does if the 37-year-old Peters has to miss some snaps again Sunday. He could decide to keep Dillard at right tackle and call upon Vaitai in Peters’ spot in an effort to avoid over-complicating things for the former Washington State star. Or he could switch Dillard back to left tackle and have Vaitai play on the right side.

Prior to Friday’s walkthrough, Pederson said Dillard “looks good. Each day he’s gotten better. He’s really settled in. He had a good day (Thursday and) expect the same today. So he’s trending in the right direction.”

Though he admitted this is one of the biggest challenges of his football career, Dillard believes he’s comfortable enough that he’ll perform well Sunday.

“I really spent the entire week just kind of visualizing the right side of my vision — what I see with my right eye — adjusting my weight and just really getting a lot of reps,” Dillard said. “(Having a week of practice) helps a lot. It works wonders.”

Dillard, who remains the Birds’ left tackle of the future, insisted he wasn’t surprised when the coaches moved him to right tackle following the Patriots game.

“I’m a backup,” he said. “I’ve got to play more than one spot.”

If he can do the job against end Jadeveon Clowney and Seattle’s defensive line Sunday, Dillard would show that he can tackle pretty much anything.

Tom Moore:; @TomMoorePhilly