Gaines injury came at pivotal time with the Bills clinging to a 17-10 fourth-quarter lead. With Gaines sidelined, Atlanta drove down the field and scored a touchdown to tie the game.
Before leaving the game, Gaines had racked up a couple of tackles.
The Bills defense has played well overall, picking off Falcons quarterback Matt Ryan and returning a fumble for a touchdown.
Shareece Wright stepped in for Gaines with Leonard Johnson remaining in the slot. Gaines has missed snaps in each game this season with various injuries but has always returned to finish the game.
The Bills lost wide receiver Jordan Matthews and core special teamer Colt Anderson to injury in the game, as well, and defensive end SHaw Lawson didn’t play. Marcell Dareus appeared limited in his return.