Allen (back) is listed as doubtful ahead of Sunday's contest against the Cardinals, Josh Weinfuss of ESPN.com reports.
Allen was held out of practice all week due to a back issue, so it's no surprise that he likely won't be suiting up in Week 2. If the Clemson product misses Sunday's contest as expected, Hunter Long will likely serve as the Rams' No. 2 tight end behind Colby Parkinson.