San Francisco 49ers running back Christian McCaffrey is going to be out for at least the next four games.

Per ESPN’s Adam Schefter, the 49ers will place the reigning NFC Offensive Player of the Year on injured reserve as he continues to deal with calf tightness and Achilles tendonitis.

The move ensures that McCaffrey, who had already been ruled out for Sunday’s game against the Minnesota Vikings, won’t be eligible to play until at least Week 6.

McCaffrey has been battling a calf and Achilles injury since at least early August.

The Achilles issue has since been identified as tendonitis by 49ers head coach Kyle Shanahan.

After missing the preseason and being listed as questionable heading into Week 1, McCaffrey was a late addition to the inactive list ahead of the 49ers’ season-opening win over the New York Jets.

Shanahan said on Tuesday that McCaffrey’s injury was something “you’ve got to be very careful about.”

Shanahan told reporters he was considering placing McCaffrey on IR after suffering his “worst day” with the injury on Thursday.

“It’s on and off, but with yesterday having the most pain, it’s something we’re going to discuss in the next 24 hours,” Shanahan told reporters on Friday.

McCaffrey led the NFL with 1,459 rushing yards while recording 21 total touchdowns during his All-Pro campaign for the 49ers in 2023.

The star running back dealt with injuries early in his career with the Carolina Panthers as he was limited to 10 games combined over the 2020 and 2021 seasons.

His injury luck improved in the 2022 and 2023 campaigns, however, as he missed just one regular-season game over those past two seasons.

In his absence the 49ers will have to lean on Jordan Mason, who has served as a backup for his previous two seasons in San Francisco. Mason helped cover for McCaffrey’s Week 1 absence by recording a career-high 147 rushing yards on 28 carries.