SANTA CLARA -- Shon Coleman, the leading candidate to be the 49ers’ backup at both offensive tackle positions, sustained a serious injury to his right ankle Saturday night, and it reportedly could end his season.

Coleman was injured when 49ers guard Najee Toran fell into his leg on a first-quarter run play in the preseason opener against the Dallas Cowboys at Levi's Stadium. The 49ers' medical staff placed an air cast on Coleman’s right foot, and he was carted off the field for further observation.

The Athletic's Matt Barrows cited a source in reporting that it's believed Coleman's injury will knock him out for the season.

Coleman came to the 49ers in an August 2018 trade with the Cleveland Browns. He did not appear in a game last season, as he remained on the 53-man roster but was deactivated for every game. Coleman started all 16 games for the Browns in 2017 after he was drafted in the third round out of Auburn.

The 49ers this offseason released Garry Gilliam, their backup tackle last year, clearing the way for Coleman to be the top backup. Gilliam remains a free agent.

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The 49ers selected Justin Skule of Vanderbilt in the sixth round of the 2019 NFL draft. Skule started Saturday night at right tackle, as the 49ers chose not to play any of their top six offensive linemen.