A 90-minute evaluation on Monday by Dr. Michael Dillingham confirmed that Robert Guerrero’s sparring injury was a partial tear in the rotator cuff of his left shoulder and that it is not career threatening.

Guerrero received an MRI on Saturday, which first revealed the tear. X-rays showed that there were no broken bones.

Guerrero met with Dillingham — the San Francisco 49ers team physician — on Monday in Redwood City, Calif.

“They looked at the MRI together, and we do know that Robert’s injury is not career-ending and that he’s going to live to fight another day,” said Mario Serrano, Guerrero’s publicist. “That’s something that’s official, and that is really important to know.

“So Robert’s going to go back on Wednesday, and we’ll know more about how long he will be out. They want to run some more tests, and there’s more evaluation that needs to be done on the reading. We’ll go over all of the scenarios then.”

Guerrero suffered the injury while throwing a low, left cross against a sparring partner during training last Wednesday evening in Big Bear, Calif., forcing the cancellation of a fight against Marcos Maidana that was scheduled for Aug. 27 on HBO.

“As we know, Robert’s going in [to the doctor] on Wednesday again to determine how long he’s going to be out,” said Golden Boy Promotions CEO Richard Schaefer.

“It seems to me that best case, he’s going to be out for two months. Worst case, he’s going to be out for somewhere from four to six months.”

Lem Satterfield can be reached at [email protected]