Robert Griffin III, shown in his final preseason appearance against Baltimore, said the end of last week’s preseason finale in Tampa “means it’s Houston week, so we’re all ready to go.” (John McDonnell/The Washington Post)

Having made it through the preseason without serious injury to a starter, the Washington Redskins set about bridging the gap in their opening-day lineup Sunday by claiming veteran strong safety Duke Ihenacho off waivers.

Washington will be thin in its defensive backfield for Sunday’s regular season opener at Houston and the Sept. 14 home opener against Jacksonville because of the NFL’s two-game suspension of starting safety Brandon Meriweather for a helmet-to-helmet hit in the third preseason game.

With NFL officials rejecting Meriweather’s appeal Saturday, given his five previous infractions for dangerous hits, the Redskins’ top priority Sunday, when teams could begin claiming players who were culled by rivals, was bolstering their ranks at safety.

Heading into the weekend, Washington’s safeties were veteran Ryan Clark, 34, second-year player Bacarri Rambo, third-year player Trenton Robinson and rookie Akeem Davis.

Davis was waived to make room for Ihenacho, a third-year pro who started 14 games for the Denver Broncos last season, but Davis may be brought back for Washington’s practice squad, which started taking shape Sunday.

Is it time to panic about the Redskins’ offensive woes or is too much being made of preseason struggles for RGIII and the first-teamers? The Post Sports Live crew offers their levels of worry. (Post Sports Live/The Washington Post)

Ihenacho tweeted the good news of his signing mid-afternoon Sunday, writing: “God works in mysterious ways! Blessed to be able to continue my journey. See ya soon DC! Let’s work”

Clark replied via Twitter that he’d be “a welcomed addition.”

The practice squad, which has been increased from eight players last season to 10, represents a second chance for eight Redskins hopefuls who had been let go the previous day, when NFL rosters had to be trimmed from 75 to 53 players.

Most notable among those extended the lifeline was running back Chris Thompson, who had intrigued coaches with his speed and elusiveness during the preseason but raised alarm because of his history of injury. At a generous 5-foot-8, Thompson was the smallest player on Washington’s roster and missed two preseason games with a low ankle sprain. His rookie season was interrupted by shoulder surgery, and he was sidelined portions of his junior and senior seasons at Florida State by a broken back and torn knee ligament.

Also signed to the practice squad were first-year center Tevita Stevens; wide receiver Nick Williams, who caught two touchdown passes during the preseason; and tight end Ted Bolser, a seventh-round pick who had been fourth on the depth chart at his position.

The defensive players named to the practice squad were cornerbacks Chase Minnifield, a second-year player from Virginia; third-year veteran Richard Crawford; safety Phillip Thomas; and rookie nose tackle Robert Thomas.

Washington’s 3-1 preseason mark was a notable achievement for first-year Redskins Coach Jay Gruden. The offense moved the ball briskly under second- and third-string quarterbacks Kirk Cousins and Colt McCoy. On defense, coordinator Jim Haslett’s starting front seven showed improvement in pressuring opposing quarterbacks, and the tackling was crisper all around.

But the starting offense remains a point of concern as third-year quarterback Robert Griffin III makes the transition to a pocket-passer role.

Washington scored 10 touchdowns in its four preseason games. None were produced by the starting offense.

Cousins threw four touchdown passes, to Aldrick Robinson, rookie Ryan Grant, veteran Santana Moss and Williams.

McCoy, who played the entire fourth preseason game, also threw four touchdown strikes: to Bolser, Williams, Grant and running back Lache Seastrunk, who was among those cut over the weekend.

Evan Royster and Silas Redd rushed for the other touchdowns.

With the first team held out of the final preseason game as a safety precaution, that means Griffin’s final throw in competition before taking the field for Sunday’s season-opener was an interception.

“We don’t want to leave the game on a negative note, ever,” Griffin conceded at the time, asked about not getting a chance to close the preseason on a positive play. “It’s like you never want to leave the gym after missing a shot.”

But he chalked up the loss at Baltimore, in which he completed five of eight throws for 20 yards, threw an interception and lost 15 yards on three sacks — as “a bad outing” and “a butt-kicking,” vowing to learn from it.

With the bulk of practice closed to the media, it’s difficult to gauge how much progress Griffin and the offensive starters have made in the past week.

He was upbeat, however, after watching the backups bolt to a 10-0 halftime lead against Tampa Bay and close with a 24-10 victory. Griffin praised the fight of the running backs battling for roster spots, the explosiveness of the young receivers and the blocking that the line afforded McCoy.

“The end of this game means it’s Houston week, so we’re all ready to go,” Griffin said outside the locker room afterward. “We’re all pumped up. Everything we do now is geared toward Houston. That’s coach’s message to us, and we’ll be ready to go.”

Asked if he would have liked one more chance to fine-tune the passing game, Griffin said he and his fellow starters fully backed Gruden’s plan for sitting them out for the finale. “When it really counts,” he said, “we’ll be out there.”