SANTA CLARA, Calif. -- For the second consecutive week, San Francisco 49ers running back Christian McCaffrey's status is uncertain as he continues to deal with calf and Achilles injuries.
In his day after game conference call, Niners coach Kyle Shanahan said McCaffrey would once again be monitored on a day-to-day basis this week as the 49ers prepare to play the Minnesota Vikings on Sunday. According to Shanahan, the Achilles is holding McCaffrey back more than his calf.
"The Achilles is tendonitis and that stuff comes and goes," Shanahan said. "And when it is acting up, it's something you've got to be very careful about."
McCaffrey was a surprise inactive in Monday night's opener against the New York Jets after he and the Niners expressed optimism for most of the week that he would be ready to play. Third-year veteran Jordan Mason replaced McCaffrey as the starter and more than held his own, posting 147 rushing yards and a touchdown on 28 carries.
After the game, Mason told ESPN's Lisa Salters in an on-field interview that he found out "maybe Friday night" that he would get his first NFL start. Shanahan said no such decision was made until Monday, when McCaffrey arrived at Levi's Stadium with his injury "bothering him a little too much where he didn't feel good about it." Shanahan added that he didn't inform Mason he was starting until Monday and suggested that perhaps running backs coach Bobby Turner or another coach told Mason he was starting as a way to "pump him up" earlier in the week.
Fellow Niners such as receiver Deebo Samuel Sr. and fullback Kyle Juszczyk said they also didn't know for sure Mason would start until Monday, but had plenty of confidence he would succeed.
"It's no surprise for me with the way he has been working in camp and how hard he runs," Samuel said. "He's going to break tackles. That's just the standard of our team. He came out here and had a great day."
The calf and Achilles first began bothering McCaffrey around Aug. 6 when Shanahan said he would miss "a couple of weeks" and sit out the preseason. The calf is an injury similar to the one that McCaffrey had in a Week 17 win against the Washington Commanders last year. At the time, McCaffrey came out of that game, did not play in a meaningless Week 18 game against the Los Angeles Rams and had a bye week before returning in the NFC divisional round against the Green Bay Packers.
But even with the injuries being similar, the situations are not given how early it is in the season.
"Christian's very diligent about that stuff," Shanahan said. "And if it was a playoff game, he made it very clear to me he believed he could go. But when you hear that type of stuff and it's not a playoff game and it's Week 1 and especially when you're dealing with the lower extremities like that, it was a tough decision... In the long run, it made it easy."
As for whether McCaffrey will play against the Vikings, that decision will likely again be made much closer to game time. There's one additional factor for the Niners to consider, as their next two opponents -- the Vikings and Los Angeles Rams -- play on artificial surfaces.
"I'll ask the player how he's feeling," Shanahan said. "If they feel good and they're ready to go, they're ready to go. If they say I feel good on grass but not on turf, that's usually a way of saying that you don't really feel that good. We'll see how he feels [Tuesday]. See the next day. And we'll see how he feels on Sunday."
Elsewhere on the injury front, Shanahan said safety Talanoa Hufanga (right knee) "has a chance" to return against the Vikings. Hufanga has been working his way back from a torn ACL suffered in November of last year and was inactive against the Jets. Like McCaffrey, receiver Jauan Jennings (ankle) and guard Aaron Banks (bruised calf) will also be day-to-day this week.