"It is what it is, you know? It's something I've got to go through and must be done," said Harris, who appeared to be in good spirits at his locker given the prognosis.
The knee appeared to bother Harris after he was flipped over near the sideline by a defender during the 17-10 preseason loss Friday night to Seattle. Harris said the knee was troubling him before that play.
"I kind of knew it. But I didn't think it was going to be season-over trouble," he said. "But it's for the best. If it's for the best and better long-term, hey, I'm all for it."
Coach Mike McCarthy was a big supporter after the running back secured the starting job down the stretch last season with 157 yards and two touchdowns in four games. Harris was signed to the practice squad in October and joined the active roster in December following a slew of injuries in the backfield.
But 2013 has been tough without Harris ever seeing a regular season snap. In June, a team physical revealed Harris had a fist-sized cyst on his lung. It was drained and removed the next day, and Harris returned home the following day. It was the only other time he had undergone surgery in his career.