Kupp, coming off a season-ending ankle injury, was sidelined most of training camp and the preseason because of a hamstring injury. He practiced three times last week, including two joint workouts with the Denver Broncos.

But Thursday, Kupp did not practice after suffering what coach Sean McVay described as a muscle strain. McVay said it was accurate to call it a setback for the 2021 offensive player of the year.

Does McVay expect Kupp to be available for the Sept. 10 opener at Seattle?

“We’re taking it a day at a time,” he said.

McVay’s tone was not ominous. And he did not sound as if he was engaging in gamesmanship. The Rams clearly are concerned, however, about the seventh-year pro’s ability to return to full strength soon.

McVay, repeating the words of team doctor Neal El Attrache, said “there’s a difference between return to play and return to performance” for players.

“And we want return to performance for Cooper Kupp,” McVay said. “And we know how special of a player, how special of a person he is. And so we want to make sure that we’re smart with that and getting him back to feeling like the Cooper Kupp that we all know and that he’s able to play the way he’s capable of.

“And whenever that is, whether that be Sept. 10 or not, we’ll continue to monitor that and control what we can control.”

If Kupp is not available for the opener, that would not bode well for quarterback Matthew Stafford and the offense, which relies heavily on Kupp as a receiver, blocker and ballcarrier.

Without Kupp, the receiving corps could include Van Jefferson, Tutu Atwell and rookie Puka Nacua or Ben Skowronek as starters.

“We want him to be out here,” Jefferson said of Kupp. “But at the same time, he has to get healthy, and he wants to be in a good mental space, to when he’s ready to get back.

“We’re hoping that he’s back for Week 1. But if he’s not, guys like me and Puka and Tutu and Demarcus [Robinson], we’ve just got to ready.”

Etc.

The Rams signed veteran kicker Brett Maher to the practice squad. Maher, a sixth-year pro, played last season for the Dallas Cowboys. He made 29 of 32 field goal attempts, but in an NFC wild-card victory over Tampa Bay, he missed four straight extra-point attempts before making the fifth. … The Rams are off Friday, Saturday and Sunday. They return to practice Monday.