SANTA CLARA >> Christian McCaffrey was ruled out of the Minnesota game Friday and could be headed for injured reserve.

McCaffrey was not on the field with teammates during a brief media window at the start of Friday’s practice.

Coach Kyle Shanahan declared McCaffrey out of the game and reversed his position earlier in the week regarding a stint on injured reserve that would mean an absence of at least four games. McCaffrey is dealing with Achilles tendinitis.

“It’s something we’re considering,” Shanahan said. “Yesterday was his worst day. He had the most pain.”

General manager John Lynch said on his weekly radio appearance on KNBR-680 that all options will be considered..McCaffrey was a game day scratch in Monday night’s 32-19 win over the New York Jets.

The 49ers (1-0) visit the Minnesota Vikings (1-0) Sunday.

McCaffrey has a calf strain, but the bigger issue is an accompanying case of Achilles tendinitis that can fluctuate daily and usually requires rest as part of the treatment.

“If that’s the right thing, that’s what we’ll do,” Lynch said. “First, we’ll see how he’s doing today after getting a good work session in yesterday, see how he responds. All options, Kyle has said, are on the table. We’re going to do what’s right for Christian, what’s right for our team.”

Shanahan, who previously spoke to the local media Wednesday, said injured reserve wasn’t yet a possibility.

“I’ve never considered that,” Shanahan said. “I considered playing him last week, so definitely not thinking about four weeks off.”

McCaffrey said he will approach every week as if he’s going to play and has strayed from specifics regarding the injury.

“My mentality is that I’m playing this week,” McCaffrey said. “That’s where I’m at. That’s my mentality every week. I’m not lying. I think as a soon as a player says, ‘Maybe I’ll play, maybe I won’t’ that’s not a good mentality to go into the week with when you’re kind of on the fence. So for me, I’m ready to go.”

That determination will ultimately be made by the medical staff with the input of McCaffrey, Lynch and Shanahan.

McCaffrey was limited in practice Wednesday and Thursday.

“It’s one of those deals that he can be feeling good one day and the next day it flares,” Lynch said. “So it’s been frustrating for Christian, I know, and frustrating for us only because h’s such a great player. Primary in our mind is the long view. Christian is such an elite player, he changes us.”

Without the NFL’s leading rusher in 2023, the 49ers dominated the Jets on the ground in Week 1, rushing for 180 yards on 38 attempts. Third-year back Jordan Mason had career highs with 28 rushes for 147 yards and a touchdown and the 49ers had a 38:40 to 21:20 advantage in time of possession.

“It’s nice to see we can function without him, function at a high level,” Lynch said.

Going on injured reserve would mean McCaffrey will miss a minimum of four more games — Sunday against Minnesota, Sept. 22 at the Los Angeles Rams, Sept. 29 at home against the New England Patriots and Oct. 6 at home against Arizona.

If sufficiently healed, McCaffrey would be eligible to play on Thursday, Oct. 6 when the 49ers visit the Seattle Seahawks.

Safety Talanoa Hufanga was listed as doubtful and Dee Winters is questionable with an ankle injury. Defensive end Yetur Gross-Matos will be active and available.

“Huf is getting there,” Lynch said. “We’ll see if we’re going to pull the trigger there. Do we cut him loose now or do we hold up? We’ll see, but very encouraged with the way he’s trending.”