Matt Maiocco provided the latest update on injured linebacker Dre Greenlaw, who has elected to have a core muscle procedure that reportedly could keep him out four to six weeks.
Dre Greenlaw is having surgery to repair a core muscle injury, and his roster spot now will be available in the short term. The 49ers officially placed Greenlaw on injured reserve Saturday morning, meaning he will not be able to return to the active roster for at least three weeks.
Head coach Kyle Shanahan and general manager John Lynch both indicated this week that Greenlaw has been dealing with this injury for some time, and after aggravating it in the 49ers' Week 1 win over the Detroit Lions, surgery has been deemed the best option.
Greenlaw had one of the biggest plays of the day for the 49ers in Week 1, intercepting a Jared Goff pass and returning it 39 yards for a touchdown. Lynch told KNBR on Thursday that Greenlaw felt the injury flare up after the pick-six.
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"It was actually on the pick-six that he kinda re-tweaked it, and at some point, we scanned it, and this core muscle injury just continued to get worse," Lynch said. "It got to the point where we felt the best interest for everyone was to go ahead and handle it now.
"It's a loss, to say the least, the good news is that all indications are we'll have him back later this season. We look forward to that. We'll have to hold the fort down until then."
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Now on IR, Greenlaw will be eligible to return in three weeks under new NFL rules. The 49ers are allowed to bring back an unlimited number of players from IR as long as that player was on the team's initial 53-man roster coming out of training camp.
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Lynch confirmed the reported four-to-six-week timeline for Greenlaw's recovery, meaning he could re-join the 49ers' defense after the team's Week 6 bye.
Marcell Harris will be called on to step up in Greenlaw's absence, as the 49ers try to weather several early injuries to critical starters.