Havenstein (ankle) has been ruled out ahead of Sunday's NFC Championship Game against the Seahawks, John Boyle of the Seahawks' official site reports.
Havenstein was designated to return from injured reserve Thursday, but will be unable to suit up for Sunday's contest. The backup right tackle was a limited participant in practice Thursday and Friday but was ultimately deemed not ready to play. D.J. Humphries will likely serve as the primary backup offensive tackle for the Rams on Sunday.