TEMPE, Ariz. — Carson Palmer was expected to be practicing Wednesday, but instead of taking snaps in his practice jersey, he was excused to see a specialist, according to Cardinals head coach Bruce Arians.

The 34-year-old slinger was lauded for his durability in 2013 , where he didn’t miss a single start. But a nerve injury to his right shoulder in the second quarter against the San Diego Chargers in Week 1 has sidelined Palmer since.

Palmer was excused from practice Wednesday so that, Arians said, he could see another specialist.

“And see if he can find an answer,” the coach said.

It is a disappointing turn of events for the quarterback, who just last week expressed confidence that he would be ready to play in Denver this weekend. He had progressed and even threw upwards of 30 and 40 yards Thursday and Friday, but Arians said the veteran regressed over the weekend.

As the coach said, “something swelled back around that nerve and it went back to sleep.”

Arians said he is not ready to declare Palmer out for this week, but noted that he needs to see the quarterback throw at full speed before he would let him play. While he’s not expected to ready to practice Thursday, there is hope for later in the week as long as the visit with the specialist goes well.

“Hopefully he’ll get there, find an answer, find a treatment and get back,” he said. “And then hopefully Friday, whatever we find out will work, and he’ll be able to go.”

After Palmer’s injury, the Cardinals are 2-0 under backup quarterback Drew Stanton, whose success has lessened the need to rush Palmer back. That said, Arians pointed out that it’s not even a possibility to hurry him back, because at this point he simply cannot throw. Until he’s ready, Stanton would continue to start and rookie Logan Thomas would be his backup.

“Drew’s up and ready to go, and everybody has all the confidence in the world in Drew,” he said. “And Logan (Thomas) is getting better.”

And the uncertainty over when Palmer will be able to play again — especially after this latest setback — could mean the team will explore putting him on injured reserve. But, Arians said, the Cardinals still view this as a week-to-week injury, meaning they’re not close to making that move yet, and would be hesitant to do it once the I.R. designation would mean he is out for the rest of the season.

Arians added that if Palmer isn’t ready soon enough to start but is ready by Sunday, he could possibly be the team’s backup in Denver.

Arizona Sports’ Adam Green contributed to this report

Follow @AZSports