Armstead was already working his way back from offseason knee surgery when he injured a leg during a joint practice with the Houston Texans on Aug. 16. He was carted back to the locker room and has not practiced since.
Dolphins coach Mike McDaniel noted Friday morning that it was Armstead's plan to play in Week 1, but he needed to protect the player from himself.
"I know his expectation has been the entire time to play Week 1," McDaniel said. "And if he has the final say, if [general manager] Chris Grier and the boys decided to fire me and make him the head coach today, he'll definitely be playing. However, I want to take a look at him this afternoon and really kind of make a concrete decision for Sunday."
Armstead did not participate in Friday's practice and will miss his fifth game since signing a five-year, $75 million contract with the Dolphins last offseason.
In his absence, the team could turn to veteran Kendall Lamm, who has been the primary swing tackle throughout the summer.
The Dolphins did have good injury news on Jaylen Waddle. Despite being a limited participant at practice earlier this week, the wide receiver does not have an injury designation ahead of Sunday's game.