John Beck will make his first NFL start since 2007 when he takes the field for the Washington Redskins against the Carolina Panthers. (John McDonnell/THE WASHINGTON POST)

John Beck’s youthful visage has appeared on “SportsCenter” and the NFL Network ever since the Washington Redskins promoted him to starting quarterback. But that move is only one of five lineup changes for Washington’s offense this week, and if Beck hopes to keep his mug wide-eyed and unmarked, he’d better hope the others work out as well.

It’s not that the Carolina Panthers’ pass rush is particularly daunting. In fact, the Panthers have just nine sacks in six games; only five teams have fewer. But Beck will be standing behind a makeshift offensive line that features three new parts. In his first start since 2007, he won’t have the protection that Rex Grossman enjoyed through the team’s first five games.

“I just want to feel confident. I don’t want to put that in the back of my head,” Beck said. “I want to be able to stand in the pocket and trust those guys just as much as I trusted the other guys — that I don’t have worry, that my backside is just fine, and I’m going to stand in there and try to deliver the football.”

The Redskins have been practicing this week with a combination of linemen who have not worked together in any game, practice or training camp workout this year.

Before the first quarter was finished last Sunday against Philadelphia, injuries had claimed left tackle Trent Williams (ankle), guard Kory Lichtensteiger (knee) and tight end Chris Cooley (finger). Center Will Montgomery was forced to move to guard.

“I don’t think I’ve ever had that happen since I’ve been coach,” Mike Shanahan said of the early losses.

The end result is an unproven combination of linemen. The left tackle has more experience playing right tackle. The right tackle earned two Pro Bowl trips as a left tackle. The center will be making his first NFL start. And the left guard has spent most of his career playing center and right guard. And if any of them struggles or suffers an injury, neither of the two linemen on the bench has ever played an NFL snap.

“We’ve talked about it all year: Continuity is so important,” said Chris Foerster, Washington’s offensive line coach. “We’ve lost a little continuity this week. But at the same time, it gives other guys the opportunity to step up.”

This week the biggest question this side of the quarterback position has been about the left tackle spot: Who would protect Beck’s blind side? Despite Jammal Brown’s experience there, Sean Locklear, an eighth-year veteran who signed as a free agent, has been practicing exclusively at left tackle this week and will get the nod Sunday.

“We’ve already moved our center to left guard,” offensive coordinator Kyle Shanahan explained. “Jammal’s been . . . playing right tackle for a couple years now. I think he’s comfortable there. It’s hard to just flip a guy. I know Jammal could do it, but it does take time. We’re trying to keep some continuity with those five guys.”

Locklear made 51 starts at right tackle in Seattle from 2004 to 2008. But injuries moved him to left tackle for parts of the past two seasons. He says even when he was playing exclusively on the right side, he still saw some work on the left. And since the Redskins signed him as a free agent this summer, he’s continued taking practice snaps on both sides.

“I played a lot over there during the preseason, mainly left,” said Locklear, a North Carolina State product who has 78 career starts, including 15 last season. “Going in there and playing last week for about three quarters, I felt pretty comfortable there. Coming in with a full week’s practice, I feel pretty good about myself.”

Locklear is plenty familiar with the Redskins’ zone-blocking scheme. In Seattle, he worked last season under Alex Gibbs and Jeremy Bates, two of Mike Shanahan’s former coaches in Denver.

Center Erik Cook also will play a key role. He was a seventh-round draft pick in 2010 out of New Mexico, and at 6 feet 6, no center in the league stands taller. Cook will not only need to get leverage on opposing defensive linemen, but he’ll need to work closely with Beck to make sure the offense runs smoothly. Fortunately, Beck said, the two played together often on the scout team the past 11 / 2 months. And if Cook needs help, the former center will be a couple of inches away.

“It’s definitely an advantage having Monty there,” Cook said. “He’s had the five games there at center. So he helps me out if he sees something wrong. But he’s given me all the control with the calls.”

Montgomery is getting comfortable with his new home as well. He played the last seven games of 2010 at right guard before taking over at center this year. “At guard, you’re in a lot more space,” he said. “At center, you’re kind of playing in the phone booth.”

The Redskins will have a pair of rookies on the bench. Tackle Willie Smith is an undrafted free agent who was inactive for the first five games, and guard Maurice Hurt is a seventh-round pick who was promoted this week from the practice squad.

“You always want to get your opportunity to get in there and show what you’ve got, so I’m pretty excited,” Smith said. “I feel like I’ve been working hard, and my hard work is going to show once I get out there.”

Staff writer Barry Svrluga contributed to this report.