The man assigned to block Schofield, Green Bay tackle Bryan Bulaga, was out of the game when Schofield rushed upfield on a second-and-6 play early in the third quarter.
Schofield had beaten Bulaga's replacement up the field on the play that would end Schofield's season. Defensive end Darnell Dockett, working against a replacement guard after Green Bay moved its regular one to tackle in response to Bulaga's injury, also got good push on the play.
Packers quarterback Aaron Rodgers sensed their pressure and broke from the pocket to his right. The chase was on.
Dockett launched his 290-pound body into the air and was horizontal to the ground as Schofield turned back to the quarterback and accelerated right into Dockett's path. The athletic Rodgers pulled into the clear as Dockett's body, now spinning like a helicopter blade, chopped down Schofield from behind in the lower left leg.
The force of the impact dropped Schofield to the ground instantly, contorting his body. Dockett's weight briefly pinned Schofield's leg to the ground as both players slid across the grass. It was clear right away Schofield would not be OK.
The Cardinals did not reveal specifics on Schofield's injury. Coach Ken Whisenhunt told reporters the injury would be season-ending, however.
The Cardinals were betting on Schofield and another young outside linebacker, Sam Acho, heading into this season.
They released veteran Clark Haggans and did not address the position in the 2012 NFL draft. Arizona was the only NFL team to emerge from the 2012 draft without selecting a player for its defensive front seven.
So, when Schofield suffered his ankle injury at Lambeau Field, the Cardinals didn't have a rising prospect to plug into the role. They had Quentin Groves, a former starter and backup in Jacksonville and Oakland. Groves, who has 22 NFL starts and 4.5 career sacks, has played roughly one-fifth of the Cardinals' defensive snaps this season. He projects as the starter with Schofield no longer available.
Arizona signed Groves in May to a one-year deal worth $700,000. The Cardinals claimed Westerman off waivers from Miami. Nash is an undrafted rookie free agent. Tim Fugger, a seventh-round pick of Indianapolis this year, is an outside linebacker on the practice squad.
Schofield had four sacks in nine starts while playing better than 80 percent of the defensive snaps. He lasted until the fourth round of the 2010 draft because he faced an arduous rehabilitation from knee surgery. Knee trouble had occasionally limited him this season.