SANTA CLARA, Calif. (AP) — San Francisco 49ers free safety Adrian Colbert likely will miss the rest of the season with a high ankle sprain he suffered Sunday.
The 49ers placed Colbert on injured reserve Monday and signed quarterback Tom Savage to a one-year contract to take his roster spot.
Coach Kyle Shanahan estimated Colbert would be sidelined for six to eight weeks. He would be eligible to come off IR for the 49ers' second-to-last game, at home against the Chicago Bears on Dec. 23.
But Shanahan talked as if Colbert, a second-year player out of Miami, will be shut down for the season. Rookie D.J. Reed will get the first opportunity to start at free safety in his absence.
"It's tough. It's part of football, though," Shanahan said. "It's not the first time that's happened. Colbert is one of those guys who got his opportunity last year because a lot of guys went down."
The 28-year-old Savage, who made nine starts over three seasons with the Houston Texans, originally signed with San Francisco last Tuesday. He was waived Saturday when the 49ers promoted defensive back Tyvis Powell from the practice squad for Sunday's game against the Rams because of injuries in the secondary.
But Savage was quickly re-signed to provide San Francisco with a third quarterback alongside starter C.J. Beathard and backup Nick Mullens. The 49ers lost Jimmy Garoppolo in Week 3 to a torn ACL.
Shanahan remained firmly committed to Beathard on Monday despite a shaky performance in Sunday's 39-10 loss to the Rams.
Beathard threw two interceptions and lost a fumble, giving him seven interceptions and three lost fumbles in five games (four starts). San Francisco (1-6) is winless since Beathard took over for Garoppolo.
"We've had 18 turnovers this year," Shanahan said. "I've watched every single one, definitely more than once. I recommend you guys (the media) do it too. You guys will see there's a lot of people involved in each one."
The 49ers have an NFL-worst minus-15 turnover ratio, and the offense is only half the problem. San Francisco has forced just three turnovers — one interception and two fumbles — in seven games.
Colbert is one of a few second-year defensive players — linebacker Reuben Foster and cornerback Ahkello Witherspoon are others — who haven't made the impact that was anticipated after their promising rookie seasons.
Addressing his group of second-year defenders as a whole, Shanahan said: "Those guys worked extremely hard in the offseason. They came in ready to take it to another level and they haven't done that so far. That stuff's hard."
Shanahan praised Colbert, however, saying the free safety was enjoying a strong game Sunday before hurting his ankle while trying to intercept interception on a deep pass in the third quarter.
NOTES: Running back Matt Breida is day-to-day after tweaking his left ankle Sunday, but "his strength is good," Shanahan said. ... Receivers Marquise Goodwin (ankle) and Pierre Garcon (knee) and strong safety Jaquiski Tartt (stinger) will be evaluated Wednesday. ... Foster (shoulder) is expected to practice Wednesday.
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