49ers’ Christian McCaffrey goes on injured reserve with calf/Achilles issue

MINNEAPOLIS — The 49ers won without Christian McCaffrey in their season opener and now must try repeating that trick for at least the next month.

McCaffrey, the NFL’s reigning rushing champion and AP Offensive Player of the Year, will be placed Saturday on injured reserve and miss at minimum the next four games to treat a calf injury and Achilles tendinitis.

The 49ers did not fill his spot on the 53-man roster, and they only called up safety Tracy Walker III as a standard practice-squad elevation for Sunday.

Next up is Sunday’s visit to the Minnesota Vikings, where Jordan Mason will make his encore in McCaffrey’s place. Mason ran for 147 yards and one touchdown in Monday night’s first career start to highlight a 32-19 win over the New York Jets.

The 49ers called on Deebo Samuel for eight carries in that opener. With Samuel’s career average of 6 yards per carry, the 49ers figure to use his wide runs to complement Mason’s power and improved vision.

Rookie Isaac Guerendo and fourth-year veteran Patrick Taylor Jr. are the other running backs on the roster, with Ke’Shawn Vaughn on the practice squad. Elijah Mitchell, McCaffrey’s backup the previous two seasons, was ruled out before this season started because of a hamstring injury.

Before flying Friday to Minnesota, the 49ers ruled out McCaffrey for Sunday’s game.

“He’s dealing with this Achilles tendinitis, which can be one of those deals where it’s feeling good one day and the next day it flares,” general manager John Lynch said Friday morning on KNBR 680-AM. “It’s been very frustrating for Christian and frustrating for us only because he’s such a great player.

“Primary in our mind is the long view,” Lynch added. “Christian is such an elite player. He changes us, makes us different. Also, it’s nice to see we can function without him. We can function at a really high level.”

McCaffrey was a game-time scratch for the opener, and because he was listed two days earlier as questionable, the NFL said Friday it found no evidence of the 49ers’ violating its injury report policy.

Trips to injured reserve scuttled McCaffrey’s 2020 and ’21 seasons with the Carolina Panthers, who dealt him midway through the 2022 season to the 49ers.

Two games into 2020, McCaffrey went on IR because of an ankle injury, then shoulder and thigh injuries were cited for him sitting out the seven games of that 5-11 season. In 2021, a hamstring injury sidelined him after three games and led to an IR stint (after two games being inactive), then he finished the final five games that 5-12 season on IR with another ankle injury.

The 28-year-old former Stanford star has suited up for every 49ers game since his trade except for Monday’s opener and this past January’s regular-season finale, also because of a calf injury, which he said Wednesday was unrelated to his current plight.

McCaffrey did not take part in the 49ers’ voluntary offseason program, then he received a two-year extension that guaranteed $24 million upon reporting to June’s mandatory minicamp. He practiced roughly a week in training camp up until Aug. 4, then took four weeks off before being limited in team drills up until Thursday’s painful session sidelined him for Friday’s walk-through and deemed him out Sunday.