The Lions ruled left tackle Taylor Decker, right guard Halapoulivaati Vaitai, safety Kerby Joseph and cornerback Emmanuel Moseley out with injuries, and listed running back David Montgomery as doubtful. None of the five practiced this week.
Decker will miss his second straight game with a sprained ankle, while Vaitai (knee), Joseph (hip) and Montgomery (thigh) suffered injuries in last week's loss to the Seattle Seahawks.
C.J. Gardner-Johnson also tore his pectoral muscle in that game and will miss most of the season.
Joseph and Gardner-Johnson finished the game despite their injuries.
With Joseph and Gardner-Johnson out, the Lions will start Tracy Walker and Ifeatu Melifonwu at safety. Penei Sewell is expected to make his second straight start at left tackle, with Matt Nelson playing right tackle and Graham Glasgow starting at right guard.
Moseley has not played this season because of knee and hamstring injuries.
"Obviously when there’s injuries guys got to step up, but for me, I think that’s what excites me is other guys get opportunity," St. Brown said. "I know some guys are itching for that opportunity and it’s their chance to get it, so I’m excited for those guys. ... When I was a rookie I played but I didn’t get that many balls or what not, but when they did come, when the opportunity came I tried to make the most of it so I know these guys will do the same so I’m just excited for that."
WHAT THEY'RE SAYING: Lions a popular pick to beat Falcons among national pundits, but not a clean sweep
This article originally appeared on Detroit Free Press: Detroit Lions' Decker, Joseph out, Montgomery doubtful vs. Falcons