SANTA CLARA, Calif. — The San Francisco 49ers placed All-Pro running back Christian McCaffrey on injured reserve because of his lingering calf and Achilles tendon injuries.

The move made Saturday means McCaffrey will miss at least four more games after already sitting out the season opener. He is eligible to return for a Thursday night game in Seattle on Oct. 10.

McCaffrey got hurt early in training camp and missed four weeks of practice before returning to the field on a limited basis last week. He was a late scratch for the opener on Monday night against the Jets and now is sidelined again after experiencing pain following practice on Thursday.

The Niners made up for McCaffrey’s absence thanks to a strong performance from backup Jordan Mason, who had 28 carries for 147 yards and a touchdown in San Francisco’s 32-19 victory over the New York Jets. Mason is set to start again Sunday at Minnesota.

After missing 23 games because of injuries in his final two full seasons with Carolina, McCaffrey had been healthy the past two seasons.

He missed only one game combined in 2022-23 — a meaningless Week 18 game last season for San Francisco when he had a sore calf. His 798 combined touches from scrimmage in the regular season and playoffs were the third most for any player in a two-year span in the past 10 years.

Now San Francisco will likely rely heavily on Mason, a former undrafted free agent out of Georgia Tech who had 83 carries his first two seasons. He had at least 10 touches just twice before the season opener, when his 28 carries were the most by a 49ers player in a regular-season game since Frank Gore had 31 against Seattle on Oct. 30, 2011.

The Niners also have fourth-round rookie Isaac Guerendo and Patrick Taylor Jr. on the active roster. Guerendo played three offensive snaps with no touches in the opener. Taylor had 65 carries for Green Bay from 2021-23.

San Francisco also elevated safety Tracy Walker III from the practice squad for Sunday’s game against Minnesota.