Reed has been dealing with hip and ankle injuries, which caused him to not be able to practice Thursday or Friday before returning to limited work on Saturday. He was listed as questionable on the injury report.
The former NFL Defensive Player of the Year took part in drills before kickoff, but his hip didn't respond well.
"Ed's hip just didn't loosen up," team spokesman Kevin Byrne said. "It was a last-second decision."
A five-time Pro Bowl selection who hadn't missed a game since Nov. 27, 2005, Reed was replaced in the starting lineup by former third-round pick Tom Zbikowski. This ends Reed's streak of 64 consecutive starts.
The second-year player from Notre Dame intercepted an Aaron Rodgers pass in the first quarter and nearly intercepted a second pass in the second quarter off a deflection.
Late in the second quarter, Zbikowski allowed a touchdown while covering tight end Jermichael Finley.
Meanwhile, Pro Bowl outside linebacker Terrell Suggs didn't make the trip to Green Bay. It's the third consecutive game he has missed since spraining his left medial collateral ligament.
The Ravens started rookie Paul Kruger in his place after announcing that Trevor Pryce would start at Suggs' rush linebacker spot. It marked the second-round draft pick's first NFL start.
The Ravens also deactivated tight end L.J. Smith (ankle), defensive tackle Kelly Talavou, fullback Charles Ali, John Beck as the emergency, third quarterback as well as offensive tackles Oniel Cousins and Tony Moll.
The Packers placed outside linebacker Aaron Kampman on injured reserve due to a knee injury.
They also deactivated former Ravens wide receiver Biren Ealy, safety Matt Giordano, linebacker Jeremy Thompson (spinal cord concussion), offensive linemen Breno Giacomini and Allen Barbre, cornerback Josh Bell, defensive end Michael Montgomery and fullback Quinn Johnson.
HOMECOMING: For Ravens long snapper Matt Katula, it was an emotional homecoming as he played his first game at Lambeau Field.
The Brookline, Wis., native and former University of Wisconsin player invited more than 50 family members and friends to attend the game.
"It's going to be fun," Katula said days before kickoff. "It's going to be awesome, and it's a Monday night game. That's special. It's been a dream for me to play up there.
"I've been in the NFL for five years, so it's going to be special to go back. Especially being from Wisconsin and growing up there, the history is in your DNA."
QUICK HITS: The Ravens return home next Sunday against the Detroit Lions. … Outside linebacker Antwan Barnes got a rare activation after several weeks of inactivity. … The Ravens' game captains were cornerback Domonique Foxworth, safety Dawan Landry, middle linebacker Ray Lewis and tight end Todd Heap. … The Packers promoted linebacker Cyril Obiozor from their practice squad. … The Ravens had only 72 yards of total offense in the first half, 24 on the ground on 11 carries. Conversely, Green Bay piled up 195 yards in the first half.
Secondary forced to play without Reed
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