Kaepernick or Gabbert?: San Francisco 49ers QB questions multiply

Quarterback Thad Lewis is out for the season with a torn ACL, San Francisco 49ers coach Chip Kelly said Monday.

In another injury-related subplot, Colin Kaepernick remained idle Monday because of what was reported to be a "dead arm."

The health matters complicate the ongoing QB battle for the 49ers, who started Blaine Gabbert on Saturday.

Lewis, a college free agent out of Duke in 2010, was hurt on a 1-yard run in the third quarter of Saturday's preseason opener against the Houston Texans.

The 49ers' No. 2 quarterback in the game, Lewis was 12 of 21 for a team-high 97 yards before being lifted for rookie Jeff Driskel.

It was unclear whether Lewis would have made the final roster, which would have been determined in part by Driskel's play in the preseason.

The 49ers' QB competition for the starting job pits Kaepernick against Gabbert. It's possible Kaepernick could be traded or released if he doesn't win the starting job, but without Lewis on the roster, there is less security for first-year coach Chip Kelly on the depth chart.

Lewis was with the Eagles last season and is the only quarterback on the current roster with experience in Kelly's offense.

Kelly has said the 49ers are not interested in free agent Nick Foles, who played for the Eagles before spending last season with the St. Louis Rams.

Driskel was 4 of 12 for 20 yards in his first NFL action on Saturday.