Fitzgerald sprained his left MCL on Sunday during a win over the Detroit Lions. On Thursday, he said his knee was feeling ''a little bit better" but did not participate in the open part of practice for the second straight day.
The 31-year-old has started 71 consecutive games, the longest active streak among NFL wide receivers, and has not missed a game since Week 13 in 2007.
Fitzgerald will likely be a game-time decision on Sunday, according to Mike Jurecki of FOX Sports.
The receiver has 46 catches for 658 yards and two touchdowns this season.
The Cardinals (9-1) play the Seahawks (6-4) in Seattle on Sunday.
- Molly Geary