Cannon was injured on the opening kickoff as one of Tennessee's core special teamers. The 28-year-old was officially placed on injured reserve Wednesday.

Cannon joined the Ravens amid a slew of running back injuries in September but only lasted a week. The 49ers then picked him up for the same reason. He appeared in 11 games for them, seeing all but two of his 162 snaps come on special teams. A scary collision on a kickoff sent him to the hospital in Week 13. Cannon wouldn't return until the NFC Championship when he resumed special teams duties. He adds depth to the Tennessee backfield but doesn't project for a role in Week 1. 

Cannon suffered the injury on the opening kickoff. Seattle safety Talanoa Hufanga's collided with Cannon's neck on the play. Players took a knee around him and an ambulance was eventually brought on the field to take Cannon from the game. Cannon was able to wave to the crowd as he was leaving the game.

The claim serves as a stinging indictment of Trey Sermon, who the team made a healthy scratch in Week 1. The loss of Raheem Mostert should have been enough to get Sermon on the gameday roster but Cannon entering the mix puts that in doubt. San Francisco added Sermon in the third round of the draft this year but Kyle Shanahan has clearly been disappointed with his performance in practice so far. Sixth-round rookie Elijah Mitchell rushed 19 times for 104 yards and a touchdown in his Week 1 debut. If Sermon is passed on the depth chart by Cannon, he can officially be written off for fantasy purposes.