The fourth-year lineman's knee bent backward awkwardly in a second-quarter collision with teammate Ndamukong Suh. He was carted off the field at Wembley Stadium to the locker room and did not return.
Now that Week 8 is in full swing, here's who else we're tracking in the latest edition of our injury roundup:
Per NFL Media Insider Ian Rapoport, St. Louis is concerned that Long tore his ACL, per a source informed of the situation. He will have an MRI on Sunday night to confirm the extent of the injury. UPDATE: Rapoport reported Monday morning that tests confirmed Long tore his ACL.
- Arizona cornerback Patrick Peterson and Philadelphia Eagles wideout Jeremy Maclin collided during Sunday's game and were both taken off the field to be evaluated. Maclin re-entered the game shortly after, but Peterson was ruled out. Bruce Arians announced after the game that Peterson is going through the league's concussion protocol.