TEMPE, Ariz. — The Arizona Cardinals’ best season in 70 years hinges on keeping Drew Stanton healthy.

No one — not Stanton, coach Bruce Arians or anyone willing to withstand a polygraph test — saw that coming.

At 8-1, the Cardinals have the best record in the NFL. But they also are playing the rest of the way with Stanton, who before this year had not thrown a pass in a regular-season game since 2010.

Stanton proved himself to teammates and fans earlier this year, when he helped the Cardinals go 2-1 while Palmer was out. Last week, he came off the bench in the fourth quarter to throw a 48-yard touchdown pass to John “Smokey” Brown.

The Cardinals’ offense won’t change with Stanton in the lineup instead of Carson Palmer, who suffered a season-ending knee injury last week against the Rams.

The game plan for Sunday’s game against the Lions will be the same as if Palmer was playing.

“Nothing’s changing because we’re playing with a different quarterback,” Arians said. “We’ve already been down this road, so we had three weeks of preparation in case something like this happened. We’re more than ready for it.

“No one has to do anything more or less; just do your job and we’ll be fine.”

The injury was a crushing blow to Palmer, who had found a home and second NFL life in Arizona. Two days before the injury, he signed a three-year contract extension that included $20.5 million guaranteed.

Palmer turns 35 in December, but the Cardinals are confident he can come back from a second knee reconstruction. They expect him to be able to participate in practice by June or July.

“I’m mentally strong and I’m going to grind this thing out,” Palmer said. “I know the mindset you need to take, and that’s the one day at a time thing and it’s baby steps.”

The Cardinals, meanwhile, are not adjusting their goals. Arians is the type of coach that doesn’t mind mentioning the playoffs. And he didn’t shy away this week when asked if he thought about the possible playoff implication of Sunday’s game with the Lions (7-2).

“Hell, yeah, it’s for the No. 1 seed in the NFC this week,” he said. “Just this week, now. Not the rest. That’s a long way off. But hell, yea it does.'”

The Cardinals signed a former player, Ryan Lindley, to become their second or third quarterback. They cut Lindley in training camp and he had been on the Chargers’ practice squad.

For now, rookie Logan Thomas is the backup, but that could change by Sunday.

Thomas was shaky in his only appearance this season at Denver in relief of Stanton — the Broncos handed Arizona its one loss this season — and Lindley might be steadier if something happens to Stanton.

“Today, Logan is the backup,” Arians said on Wednesday, “and we’ll see how Ryan progresses back into our offense.”

SERIES HISTORY: 63rd meeting, Lions lead 31-26-5, but the Cardinals have won the last five meetings and 10 of the last 13. The Cardinals beat the Lions, 25-21, in week two. It was coach Bruce Arians’ first victory with the team. The Lions led, 21-13, in the third quarter. Calvin Johnson had a 72-yard touchdown reception. After trailing 21-13, the Cardinals scored on three of their next four possessions to win.