THOUSAND OAKS, Calif. — Case Keenum waited five years to begin an NFL season as a starting quarterback. When he finally got the chance with the Los Angeles Rams, his first start was haunting.

“I think that I was seeing ghosts,” Keenum said Wednesday. “I was seeing things that weren’t there. I wasn’t trusting myself and my abilities. I tried too hard.”

And now Keenum’s job status is increasingly tenuous after just one week.

The Rams can’t wait much longer to cure the profound offensive ineptitude of their opening 28-0 loss to San Francisco. Their official homecoming game against the Seattle Seahawks looms Sunday, and Keenum likely must improve sharply and quickly to persuade the Rams not to play No. 1 pick Jared Goff immediately.

Keenum’s 17-for-35 performance for 130 yards and two interceptions was just one faulty part of a creaky Los Angeles offense that produced 10 punts and a turnover on downs.

With the 49ers loading up their run defense while daring Keenum and his receivers to beat them, the Rams were the only NFL team that couldn’t score a point on opening weekend, and they couldn’t even get in the red zone. The Rams went 3 for 15 on third downs, with Keenum repeatedly throwing to receivers who weren’t far enough downfield to move the sticks.

“Case, he made some plays, and then missed some opportunities,” coach Jeff Fisher said. “But every game you watch, quarterbacks are missing opportunities. We have to just make sure we take advantage of those opportunities when they’re there.”

Keenum believes the solution to the Rams’ problems centers on confidence — specifically his own.

“Just trust what you see and let it fly,” Keenum said. “That’s what I’m going to do. I’m going to trust … my protection, my mechanics, my rules, my footwork, and trust what I see. Trust the guys out there.”

Kenny Britt had four catches for 67 yards — more receiving yardage than all of his teammates combined. Even Britt realizes the Rams can’t rely on the passing game to win.

“We have to do what we do best: Run the ball and run it well,” Britt said. “That will loosen it up on the outside, and we can take a couple of shots downfield and take that eighth man out of the box.”

The results weren’t exactly a surprise after the Rams finished 32nd in the NFL in total offense and passing offense last season, and then didn’t anything in the offseason beyond rookies Tyler Higbee, who started at tight end, and Goff. Fisher said he still hasn’t decided whether Goff will move up to become the backup quarterback Sunday.

Fisher said the Rams’ new play-caller, offensive coordinator Rob Boras, emerged from the game frustrated with himself. The Rams continually failed to create running room for Todd Gurley, and that problem is only likely to get worse against Seattle’s vaunted defense, which limited Miami to 10 points in its defense-dominated opener.

Gurley didn’t participate in the Rams’ brief workout Wednesday after carrying the ball 17 times for 47 yards in the opener. The Rams barely used Gurley in the preseason to keep him healthy, but his fresh legs weren’t much good against a San Francisco defense that smothered him, particularly between the tackles.

Britt attributed many of the Rams’ problems to opening-night jitters. After eight months of uncertainty and moving, the regular season’s arrival might have caught the Rams thinking too much instead of playing instinctive football.

“That will change up this week,” Britt said. “You realize it’s only the first game, and everybody is always overexcited when you come into the first game. You don’t want to overthink stuff. You don’t want to miss stuff. You don’t want to see one thing and then miss the next thing, so I know things will calm down for all of us.”