49ers quarterback Thad Lewis out for season after suffering ACL tear

SANTA CLARA, Calif. - San Francisco 49ers quarterback Thad Lewis will miss the 2016 NFL season after suffering a torn left anterior cruciate ligament in Sunday's preseason opener against the Houston Texans.

Niners coach Chip Kelly confirmed the injury on Monday afternoon.

"I'm just really disappointed for him because I thought he played well yesterday," Kelly said. "We would like him to stick around."

With 49ers quarterback Colin Kaepernick nursing a fatigued right arm; Lewis was the first off the bench behind starter Blaine Gabbert against Houston. Lewis took over on the team's fourth offensive series and played well into the third quarter.

On his final snap before departing, Lewis scrambled from pressure for a 1-yard gain. Lewis was hit as he went to the ground but Kelly said Lewis didn't believe he was hurt that bad on the play.

Lewis had a slight limp as he went to the locker room and seemed to be in good spirits as he left Levi's Stadium on Sunday night. But Kelly said the 49ers received the official confirmation of the injury on Monday morning and hadn't yet had the chance to discuss what comes next.

"We just lost Thad today, which is disappointing for us," quarterbacks coach Ryan Day said. "We really felt like we were creating depth at the position and then we lose Thad so it's an obstacle we've got to overcome but that's part of coaching in the NFL. Nobody else cares so although it bothers us, we have to come up with a new plan moving forward."

Lewis played the most snaps of any 49ers offensive players before departing. He finished 12-of-21 for 97 yards and rushed four times for 10 yards.

Before the injury, Lewis was considered to be in competition for a potential third quarterback spot on the roster against rookie Jeff Driskel. Lewis got the first chance to replace Gabbert on Sunday because Kaepernick has been unable to throw for the past few days because of tightness in his arm and shoulder.

Although he won't play this season, Lewis has told the coaches he would like to stay around the team for his rehabilitation. As a member of the Philadelphia Eagles in 2015, Lewis is the only quarterback on the roster with experience playing in Kelly's offense and his knowledge of it could be useful for the remaining healthy quarterbacks.

"Yeah, he can help out," Day said. "He has experience in the system, he was in Philly with us last year, he has a dynamic personality and he has a really good chemistry with the guys on our team and so he mentioned to me today that he would like to stay around and be around the program during the rehab which would be great for us. We can use that and have him around and his experience would be great."

Until Kaepernick returns, the Niners will lean on Gabbert and Driskel to handle the bulk of the repetitions though Kelly indicated that further discussions on the quarterback depth would take place. The 49ers are hopeful that Kaepernick will be able to practice this week against Denver but that remains uncertain.