San Francisco 49ers star running back Christian McCaffrey is set to miss his second straight game to start the 2024 season.

Per ESPN’s Adam Schefter, the 49ers ruled out McCaffrey for Sunday’s game against the Minnesota Vikings due to a calf injury and Achilles tendonitis.

49ers head coach Kyle Shanahan told reporters the team is considering putting McCaffrey on IR, which would sideline him for a minimum of four games.

McCaffrey sat out San Francisco’s season opener against the New York Jets because of the injuries. NFL Network’s Ian Rapoport reported on Wednesday that he was “a long shot” to play in the team’s Week 2 matchup against Minnesota as he continued his recovery.

Shanahan told reporters during a conference call that the 28-year-old would be monitored on a day-to-day basis leading up to the Vikings game because of the uncertain nature of his Achilles issue.

“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 is coming off an incredible 2023 campaign in which he earned the NFL Offensive Player of the Year award after leading the league with 1,459 rushing yards, 2,023 scrimmage yards and 21 total touchdowns. He helped propel the 49ers to an appearance in Super Bowl LVIII, where they lost to the Kansas City Chiefs.

San Francisco rewarded McCaffrey with a two-year contract extension worth $38 million following the 2023 season. Unfortunately, his injury issues arose in August, limiting his participation in training camp and keeping him out for the entire preseason.

In McCaffrey’s absence, Jordan Mason impressed in his first career start with 28 carries for 147 yards and a touchdown to help lead the 49ers to a 32-19 win over the Jets.

With McCaffrey being forced to miss more time, Mason has proven to be capable of filling the workhorse role in San Francisco’s backfield.