Mason suffered the shoulder injury on a 14-yard run early in the second quarter against Seattle and returned for one more carry near the start of the third quarter before spending the rest of the game on the sideline with a wrap on his shoulder.

San Francisco managed to survive without him, turning to former undrafted free agent Patrick Taylor and rookie Isaac Guerendo to carry the load. Guerendo iced the win with a 76-yard run in the game’s final two minutes, setting up a six-yard Kyle Juszczyk touchdown run to seal the victory.

The previously unknown Mason started 2024 with a bang, rushing for 147 yards and a touchdown on 28 carries in the 49ers’ season-opening win over the New York Jets on a night when most were surprised to see McCaffrey standing on the sideline in street clothes. McCaffrey has yet to play a down in 2024, but Mason has managed to replace him quite nicely, carrying the ball 114 times for a league-best 609 yards and three rushing scores.

If any franchise is capable of finding a replacement in the backfield and scheming up ways for him to succeed, it’s the 49ers, a team that has taken the likes of Raheem Mostert, Elijah Mitchell, Jeff Wilson and Matt Breida and turned them into productive backs. Luckily, it sounds as if they won’t quite need to do that again, thanks to the good news on Mason.

Elsewhere on San Francisco’s offense, Shanahan said that he expects to open Ricky Pearsall‘s practice window next week, while McCaffrey is not expected to return just yet from his Achilles injury.