GLENDALE, Ariz. — The Los Angeles Rams’ owner, Stan Kroenke, stood on the sideline of State Farm Stadium in a tan suit with his team’s general manger, Les Snead, and its chief operating officer, Kevin Demoff.

Kroenke and two of the three men he has entrusted to construct a Super Bowl-caliber organization — who have tried to do so with the most aggressive approach in the N.F.L. — watched the defensive backs warm up next to an ESPN production tent and broadcasters.

That position group’s best player, Jalen Ramsey, was one of five players unavailable Monday because they were placed on the Covid-19 reserve list. The opponent, the Arizona Cardinals, humiliated the Rams two months ago on their own field, and the circumstances were aligned for it to happen again.

If it did, Kroenke would have seen his team suffer four prime time embarrassments in six weeks. That would have sparked more chatter of whether the bold choices his lieutenants made of shunning draft picks for stars were justified.

At least for now, those questions can wait.

The short-handed Rams (9-4) defeated the Cardinals, 30-23, on Monday night, quelling a mounting narrative that the team was unable to beat quality opponents despite boasting a roster that resembles the N.F.L. version of the Hollywood Walk of Fame. The Cardinals (10-3) still lead the N.F.C. West, but they relinquished the conference’s No. 1 seed. And as the playoffs approach, the result escalated the race for the division.

“We want to continue to be totally in and completely present, enjoy this, but let’s keep building,” Rams Coach Sean McVay said. “You want to continue to be relevant, but you also want to make sure that you’re improving so that if you do give yourself an opportunity to play after the 17-game regular season you’re playing your best ball.”

Los Angeles stood firm when Arizona recovered an onside kick with 34 seconds remaining in regulation. Instead of spiking the ball to preserve time after a completion, Kyler Murray questionably took the snap, which he said was a miscommunication between him and the offensive line. Defenders forced him to scramble, and he soon fell in Aaron Donald’s waiting arms for a sack. Donald, seemingly exhausted from a stellar performance, raised his hands and took off his helmet as he left the field.

Donald secured three sacks, two of them in the first half. The Rams needed a spectacular outing from him and all their starters amid the absences. Donald said Ramsey texted him that morning about the positive coronavirus test. The Rams placed Ramsey and tight end Tyler Higbee on the Covid-19 list on Monday after already adding running back Darrell Henderson, right tackle Rob Havenstein and backup cornerback Dont’e Deayon over the weekend. That caused the team to hustle and adjust.

“I think he did a great job adapting,” said quarterback Matthew Stafford, who threw for 287 yards and three touchdowns. “I think the guys that we needed to step up and come in and play well did that. It’s a testament to our coaching staff and then our players going out there and executing.”

On a large stage, the onus especially fell on Stafford — who had struggled in similar scenarios — and Snead’s flashy midseason acquisitions, Von Miller and Odell Beckham Jr. They responded. Stafford did not commit a turnover after throwing interceptions that were returned for touchdowns in three other nationally televised games.

For the Cardinals, Murray threw for 383 yards and two interceptions. He also rushed for 61 yards. “Obviously, we lost and everybody wanted to win,” Murray said. “It was a big night, a big game for us, but I’m not discouraged.”

Beckham caught six passes for 77 yards and a touchdown, and Miller posted four tackles, including a critical one on fourth down. Beckham’s score was his third touchdown in his third game with the Rams since joining in free agency after his contentious exit from the Cleveland Browns. His production showcased that he is still an elite threat when used properly.

“We often forget — there’s business, there’s politics, as always in this game — but this is big kids at heart who love football,” Beckham said.

The Rams entered Monday 2-4 against teams with a winning record, and had a three-game losing streak against the Titans, 49ers and Packers before drumming the Jaguars last week.

All of their losses generally followed the same formula. Opponents were noticeably more physical — in their losses, the Rams averaged 133 rushing yards allowed. Opposing quarterbacks dispersed the ball quickly — Murray, Ryan Tannehill, Jimmy Garoppolo and Aaron Rodgers threw passes in just 2.5 seconds on average, according to N.F.L. NextGen Stats. Releasing the ball so rapidly negated the Rams’ potent pass rush.

“Our goal is to try to build a team that stresses opposing teams and applies pressure to opposing teams,” Snead said in a news conference after acquiring Miller.

Donald, a three-time N.F.L. defensive player of the year, succeeded early for the Rams on Monday night. He credited that to a defensive scheme and blitz packages that created one-on-one matchups allowing him and others to penetrate the backfield. In Ramsey’s absence, Darious Williams, normally the team’s No. 2 cornerback, also played well, with key pass breakups

“We had a game plan, and we stuck to it,” Donald said.

The score was tied, 13-13, at halftime before the Rams pulled away in the third quarter. Stafford lofted a perfect pass to Van Jefferson for a 52-yard touchdown and also connected with Cooper Kupp, who leads the league in every major receiving category, for a four-yard score. Kupp caught 13 of his 15 targets for 123 yards.

But Arizona responded. James Conner, who accounted for 125 yards from scrimmage, scored his second rushing touchdown at the start of the fourth quarter, slicing the Rams’ lead to 27-20. The Rams answered with a field goal that ended a drive that chewed over six minutes of clock. The Cardinals then kicked their own field goal before recovering the onside kick.

Arizona now faces a winnable game against the Lions before playing the Colts, Cowboys and Seahawks — competitive matchups that will impact whether they have home-field advantage for a playoff game.

“This group, we’re frustrated, we’re disappointed, but we’ll get back,” Coach Kliff Kingsbury said.

The Rams are seeking to play at their home venue on Feb. 13, when SoFi Stadium hosts the Super Bowl. Snead’s strategy of forgoing draft picks in trades for Stafford, Ramsey and Miller have heightened their need to win now. But they feel they are on the right path.

“We wanted to go out there and get the job done,” outside linebacker Leonard Floyd said. “We got tired of the noise.”