Martin's knee injury not an ACL tear

San Francisco 49ers third-round draft pick Marcus Martin did not suffer a season-ending left knee injury in Sunday’s exhibition victory over the San Diego Chargers as widely feared, coach Jim Harbaugh said in a news conference Monday.

Martin, selected No. 70 overall out of USC, is the 49ers’ backup center behind Daniel Kilgore and went down in the fourth quarter. An MRI ruled out an ACL tear though Harbaugh would not put a timetable on the rookie offensive lineman’s return.

The San Francisco Chronicle reported Martin dislocated his kneecap and would be sidelined for eight weeks.

“I don’t think that was exactly the medical term for it,” Harbaugh said.

“We’ll just hold off on any definitive comments.”

Adam Snyder, Joe Looney and Dillon Farrell were mentioned by Harbaugh as three other offensive linemen able to play center.

Martin, who could be a candidate for the Injured Reserve/Designated to Return list along with nose tackle Glenn Dorsey, suffered dislocated a kneecap in his final college game last November. It’s an injury that many believe make players more susceptible to the same type of damage in the future.

He Tweeted the following after Sunday’s exhibition:

Also, safety Bubba Ventrone’s hamstring injury suffered Sunday was “not a serious one,” Harbaugh said.