The San Francisco 49ers are dealing with all sorts of injury concerns in their offensive backfield.

Star running back Christian McCaffrey and fellow running back Jordan Mason were each placed on IR this week. McCaffrey is dealing with a PCL injury while Mason has an ankle injury.

That meant the 49ers had to rely on rookie running back Isaac Guerendo for Sunday’s game against the Chicago Bears and for the rest of the regular season.

As the starter against the Bears, Guerendo performed admirably on Sunday. Guerendo had 15 carries for 78 rushing yards and rushing scores of 1 and 4 yards. The Louisville product also caught two passes for 50 yards.

However, Guerendo had to leave the 49ers’ game against Chicago with a reported foot injury. Guerendo’s return was considered questionable.

Fourth-year pro Patrick Taylor serves as the 49ers’ backup running back. After Guerendo’s retirement due to injury, Taylor immediately reached the end zone with a 3-yard rushing score, extending the 49ers’ commanding lead over the Bears to 38-13.

However, given the health of San Francisco’s backfield, this is an important situation to watch with Guerendo.

This article originally appeared on Niners Wire: 49ers suffer latest RB injury against Chicago Bears