The 49ers are bringing in former Humboldt State running back Ja’Quan Gardner to provide assistance to help the team get through the preseason finale Thursday night against the Los Angeles Chargers.

If Gardner passes his physical, San Francisco will sign him, a league source said.

On Monday, 49ers receiver Max McCaffrey posted photos on his Instagram story after undergoing surgery on his left foot. McCaffrey got off to a good start in training camp, but was sidelined by the injury before the team’s first preseason game.

Photo Courtesy: @maxmccaffrey87/Instagram

Photo Courtesy: @maxmccaffrey87/Instagram

With Gardner’s signing, the 49ers will be at the 90-player limit entering the final game of the preseason. All NFL teams must get down to the regular-season roster limit of 53 players by Saturday, 1 p.m.

Teams generally do not give extensive playing time in the final preseason game to players who figure to be on the regular-season roster.

 

The 49ers will not suit up starting running back Jerick McKinnon (calf) or backup Matt Breida (shoulder) to give them the best chance to be ready for the regular-season opener on Sept. 9 against the Minnesota Vikings.

Joe Williams is questionable to play on Thursday after sustaining a fractured rib in the 49ers’ exhibition game against the Houston Texans on Aug. 18.

Veteran Alfred Morris and special-teams ace Raheem Mostert may not see much action on Thursday, as they are likely to be on the team’s 53-man roster to open the season. Second-year player Jeremy McNichols and undrafted rookie running back Jeff Wilson could split the bulk of the playing time with Gardner in a reserve role.

Gardner (5-foot-7, 205 pounds) took part in the 49ers’ rookie minicamp as a tryout player. He holds Humboldt State record for most yards rushing in a career (5,426) and season (2,266) and most touchdowns in a career (93) and season (25). Humboldt State recently announced this is the last season the university will field a football team.