SANTA CLARA (AP) — The San Francisco 49ers released quarterback Matt Barkley on Friday, clearing the way for rookie C.J. Beathard to open the season as the backup to Brian Hoyer.

The Niners had been debating whether to keep two or three quarterbacks but opted for only two after a successful preseason for Beathard. The third-round pick out of Iowa posted a 107.7 passer rating in exhibition games and also scored on a 62-yard run Thursday night against the Los Angeles Chargers.

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Barkley threw only 21 passes and didn’t play at all in the preseason finale as coach Kyle Shanahan said he knew what Barkley could do and wanted to see younger quarterbacks like Beathard and undrafted rookie Nick Mullens, who could be a candidate for the practice squad.

San Francisco released 15 players in all Friday and also waived cornerbacks Prince Charles Iworah and Will Redmond with injured designations. The team must still trim 18 more players to get down to the 53-man limit by Saturday’s deadline.

The team also released running back Tim Hightower, who averaged 1.8 yards per carry in the preseason and fell behind three untested backs on the depth chart behind starter Carlos Hyde.

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Raheem Mostert, who has been in seven organizations since entering the league as an undrafted free agent in 2015, has one career carry. But he ran for 115 yards on 19 carries, had an 87-yard touchdown catch and played well on special teams this preseason, which could warrant him a spot on the roster.

Fourth-round pick Joe Williams and undrafted rookie Matt Breida are also in the running for roster spots and San Francisco could keep all four players. Williams lost a fumble Thursday night and has had trouble holding onto the ball in practice at times this summer.

“That’s always a big mark,” Shanahan said Thursday. “If you can’t hold onto the ball it’s very tough to play in this league. He’s had a few of them so that definitely is alarming. Something that we have to get fixed. Wish he could’ve stayed back in the game more. He hurt his ankle a little bit there at the end, so we had to get him out.”

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The other players left go by San Francisco were offensive linemen Tim Barnes, Andrew Gardner, Andrew Lauderdale and Norman Price; defensive backs Will Davis and Vinnie Sunseri; receivers Louis Murphy and Tim Patrick; running backs Kapri Bibbs and Tyler McCloskey; defensive lineman Leger Douzable; linebacker Shayne Skov; and kicker Nick Rose.