SANTA CLARA, Calif. (AP) With Colin Kaepernick dealing with tightness in his throwing shoulder and Thaddeus Lewis out for the season with a knee injury, the 49ers signed free agent quarterback Christian Ponder on Tuesday.

Ponder, 28, hasn't appeared in an NFL game since October 2014 with the Minnesota Vikings.

San Francisco was down to two healthy quarterbacks, Blaine Gabbert and Jeff Driskel, as the team traveled Tuesday to Denver for two joint practices with the Broncos ahead of their preseason game Saturday.

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Kaepernick hasn't thrown during practice since Aug. 10 and was held out of the preseason opener Sunday against the Texans. Prior to the injury, he was competing with Gabbert to start under first-year coach Chip Kelly.

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