Head coach Bruce Arians said Wednesday that Dockett's injury was non-contact.
"You just put your foot in the ground and it's over," Arians said.
Dockett will have surgery as soon as possible, Arians said, and the plan is for Dockett to rehab in Arizona. But Dockett won't be a ghost in the locker room this season. Arians wants him on the sideline for moral support.
"His spirit and leadership is something we need and is something we don't want to lose," Arians said.
Dockett has missed just two games because of injuries in 10 seasons.
"That's an amazing feat," Arians said. "Just shows how hard he trains and keeps himself in top physical condition all the time."
As had been expected, Arians announced that defensive end Frostee Rucker will replace Dockett in the starting lineup and he'll be backed up by rookies Ed Stinson and Kareem Martin. With nose tackle Alameda Ta'amu returning to practice Wednesday, Arians said another option will be moving nose tackle Dan Williams to defensive end on a few plays, giving Arizona options to fill Dockett's void.
Arians called Stinson's process "great." The Alabama product drafted in the fifth round in May's NFL draft is the likely long-term successor to Dockett. Martin, however, has struggled against the run but been solid in the pass rush, Arians said.
Arians said the Cardinals would be working out "some guys" Wednesday, one of which was expected to be nine-year veteran Isaac Sopoaga.
"We'll just keep moving on like we always do," Arians said. "One injury is not going to change who we are or what we do."