Allen left the field with trainers with about 11 minutes left in the first half after a helmet-to-helmet collision with teammate Demario Davis. Allen had a tackle and a pass defended before exiting.
It's unclear how much time Allen will miss. Per the NFL's concussion protocol, he must pass a neurological exam before he can return to practice.
Cornerbacks Dexter McDougle and Dee Milliner have also sustained injuries. McDougle is out for the season after tearing his left ACL, and Milliner is questionable for Week 1 with a high left ankle sprain.
Those injuries elevated Allen and Walls to starting roles for the Giants game.
Allen in entering his third NFL season after the Jets selected him in the seventh round of the 2012 NFL draft. He started nine games for New York at safety last season, recording 60 combined tackles, one interception and one sack.
- Ben Estes