Washington Redskins coach Mike Shanahan gave backup offensive linemen Willie Smith and Tyler Polumbus high marks for their performances against the New England Patriots as both stepped in for the team’s veteran tackles.

Polumbus — a fourth-year pro who signed with Washington on Nov. 9 — made an unexpected start at right tackle after Jammal Brown suffered a groin injury during pregame warmups. With Trent Williams suspended for the season, Smith, a rookie out of East Carolina, initially rotated series at left tackle with eight-year veteran Sean Locklear, but ended up playing the entire second half after impressing coaches.

“I thought Tyler Polumbus came in and did an excellent job for [limited] practice during the week,” Shanahan said. “We switched series with Sean Locklear and Willie Smith and I thought they did a good job as well. . . . We wanted to take a little pressure off of him in not throwing him right away and starting the game in case he made a few mistakes and so we alternated series. When Willie started playing well, we kept him in there and I thought he did a good job.”

Polumbus made one start at left guard last month, and spent the week working at both guard and right tackle. He has spent much of his career at right tackle, starting a combined 15 games at that spot for Denver and Seattle in 2009 and 2010, respectively.

“It was pretty crazy when Jammal went down in warmups,” Polumbus said. “Obviously, it’s pretty unexpected for a player to get hurt in warmups. But obviously, you just take the opportunity to go in there and play. . . . It took me the first quarter. I had a few plays that I would like to do a little bit better on. But I started to get in more of a groove, and it started to get better. Thought I did pretty good.”

Sunday marked the first action of the season for Smith, who had previously dressed for only one game. His day got off to a rough start. After watching the first series, he came in and three plays in, gave up a sack to former Redskins defensive end Andre Carter in the end zone. Rex Grossman fumbled on the play, and Vince Wilfork recovered for the first touchdown of the game.

“It’s the worse feeling ever, man, to see you gave up a sack, and then you look back and see he fumbled. That’s always bad,” the 6-foot-6, 290-pound Smith said. “It was more of what I did. I got back there and started to lean, and when I leaned, he took advantage and he swam over me.”

Shanahan said Smith got better as the game progressed. Smith felt good about his progress, but said the surrendered sack hurt.

“I was expecting to go out there and play a solid game, no sacks, no pressures, but I guess I set the standards real high,” Smith said. “I want to be good.”

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Redskins’ can’t keep up despite season-best offensive showing

Game summary: Patriots 34, Redskins 27