The Arizona Cardinals have a hard time beating San Francisco. Now they have a distraction to deal with, too.

Cardinals running back Jonathan Dwyer was arrested Wednesday and accused of assaulting his wife. Police say he head-butted her, breaking her nose.

The Cardinals tried to move on, placing Dwyer on the reserve/non-football illness list. But the issue remains a backdrop to this matchup of NFC West foes.

The Cardinals have called this a rivalry. That's a tough label to justify because Arizona has beaten San Francisco once in the last 10 tries. Arizona coach Bruce Arians certainly doesn't think it is.

"It's kind of like the Browns and the Steelers," he said. "When you beat them 10 times it's a rivalry for one team but not the other. I'd imagine they (the 49ers) think the Seahawks are their rival, not us."

Arizona's lone victory over San Francisco since 2008 came three years ago.

This time, the Cardinals enter the contest ahead of the 49ers in the standings. Arizona is 2-0 after beating the Giants on the road 25-14. San Francisco is 1-1 after losing to Chicago 28-20 to spoil the debut of the 49ers' swanky new Levi's Stadium.

"We all understand we're in the bouncing back business," 49ers coach Jim Harbaugh said. "That's part of our job description. Nobody does it better than our team. Tough loss. Fortunately, we're a tough team."

Each team has a significant injury: Arizona quarterback Carson Palmer (nerve damage in his throwing shoulder), San Francisco tight end Vernon Davis (ankle).

If Palmer can't go, Drew Stanton will get the start. Last week was the first time Stanton played in a regular-season game in four years.

Davis was on crutches early in the week, but an MRI showed no significant damage.

"I don't think there's any doubt Vernon will be out there," Arians said. "It's too big of a game for them. They definitely don't want to lose two in a row. Especially, they want to win the division, like we do. It'll be all hands on deck."

Here are things to look for when the 49ers and Cardinals meet.

CONFIDENT STANTON: If Stanton goes, he will play with the confidence of managing a tough game on the road a week ago.

His numbers weren't great: 14 for 29 for 167 yards. But he was not intercepted.

"I think that once you get a chance to get out there and see it unfold, it is more comforting going through this week for sure," Stanton said.

ELLINGTON'S CONDITION: Arians says running back Andre Ellington is "fine," even though he missed practice time for the second week in a row with what he's described as a partially torn tendon in his left foot.

Despite the injury, Ellington showed some of his old acceleration ability against the Giants, rushing for 91 yards in 15 carries.

With Dwyer's absence, Stepfan Taylor moves up to backup running back.

TIGHT END DEPTH: Davis hobbled out to the weight room Wednesday still using crutches for his injured left ankle, and also was listed on the injury report with a knee issue.

Backup tight end Vance McDonald also sustained a knee injury in a 28-20 loss to the Bears last Sunday night, though neither he nor Davis had any structural damage. McDonald was optimistic he would play.

Derek Carrier is the only healthy tight end.

TURNOVERS VS. TAKEAWAYS: San Francisco has had two drastically different games so far. It realizes it must take care of the ball to bounce back against Arizona, as has been a regular pattern under fourth-year coach Harbaugh.

The 49ers forced four turnovers in a season-opening win at Dallas, getting three interceptions against Tony Romo in as many Cowboys possessions.

In Sunday's stunning loss to Chicago that spoiled the debut of the new stadium, the Bears rallied behind Jay Cutler's three fourth-quarter touchdown passes. Colin Kaepernick threw three interceptions and lost a fumble. San Francisco also hurt its cause with 16 penalties for 118 yards, and the Bears got six of their 19 first downs via penalty.

By contrast, last week against New York, the Giants had four turnovers, Arizona none.

ESTABLISHING THE RUN: The 49ers know they must get Frank Gore and rookie Carlos Hyde involved. That begins with the offensive line doing its job.

There were breakdowns on offense all around against the Bears. San Francisco managed five of its 19 first downs on the ground, finishing with 127 yards rushing.

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AP Sports Writer Janie McCauley in San Francisco contributed to this report.