FLOWERY BRANCH, Ga. -- Atlanta Falcons quarterback Tua Tagovailoa has been ruled out for Sunday's season opener against the Pittsburgh Steelers with an oblique injury, the team announced Friday. Cooper Rush will get the start in Week 1, coach Kevin Stefanski said.

Tagovailoa appeared to grab at his side or back in discomfort after a pass during the media viewing period of practice Thursday. Stefanski said Tagovailoa is considered week-to-week. "Disappointed for him, obviously," Stefanski said. "He's a very competitive person, so disappointed. But he's going to rally behind Coop and do everything he can to help Coop."

Rush took all the first-team offense reps Thursday and did all the passing in drills during the media viewing portion of practice Friday. "That's the life of a backup quarterback," Stefanski said. "There's been great guys over the course of history that do an excellent job of staying ready so they don't have to get ready and step in."

Tagovailoa was named the Falcons' starter Monday after a competition with Michael Penix Jr., who communicated to the team that he did not feel ready for live game action as he continues to work his way back from left ACL surgery in November. Penix will be listed as inactive Sunday. Rush, 32, was signed by the Falcons on the eve of training camp.