Mac Jones, playing instead of the injured Brock Purdy, passed for 342 yards and two touchdowns for the 49ers (4-1), who won in OT after a frantic fourth quarter featuring Piñeiro’s tiebreaking 59-yard field goal with 2:52 left, Williams’ subsequent goalline fumble and Joshua Karty’s tying 48-yard field goal for the Rams (3-2) with two seconds to play.The Rams gave the ball to San Francisco to begin overtime, and Jones drove to set up Piñeiro’s third field goal with 5:51 left.Jones took a battering from the Rams defense and appeared in severe discomfort as he left the field before Piñeiro’s clinching field goal. He doubled over in apparent pain on the sidelines and appeared to have trouble breathing. He was also limping earlier in the game after absorbing several blows.“That’s what happens when you don’t practice for a couple of weeks so that’s my fault,” said Jones with a smile after the game.