The injury bug continues to hit the 49ers.

Starting right tackle Mike McGlinchey is out four-to-six weeks, 49ers coach Kyle Shanahan revealed Wednesday. He will undergo arthroscopic surgery on his left knee.

After being selected by the 49ers with the No. 9 pick in the 2018 NFL Draft, McGlinchey has started every game at right tackle. He has become a dependable force on the 49ers offensive line, which, with Joe Staley out for another month or so, is now missing both its starting tackles.

Daniel Brunskill, who spent the past two seasons on the Atlanta Falcons practice squad, likely will be next man up to replace McGlinchey on the right side of the line.

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The 4-0 49ers already have their work cut out for them against the defending NFC champion Los Angeles Rams on Sunday. Now, they'll have to do so undermanned.