Moore pulled up sore in his right hamstring after kicking the ball in the first quarter of Collingwood's win over GWS on Friday night.
The 30-year-old, who was playing his first game of the year after a pre-season calf injury, received treatment and played out the game.
Coach Craig McRae conceded Moore was "not right" and expected him to miss at least Thursday's clash with Brisbane at the Gabba.
But scans showed Moore had both a hamstring strain and an inflamed bursa behind his knee, ruling him out for three-to-four weeks.
Moore will miss at least the Brisbane clash and games against Fremantle and Carlton, while the key defender will be in a race against time to face Essendon on Anzac Day.
Collingwood then face Hawthorn on April 30.
"We are obviously disappointed for Darcy," Collingwood football boss Charlie Gardiner said.Â
"Scans yesterday showed he has sustained a low-grade hamstring strain along with an inflamed bursa behind his knee, which is expected to keep him out for the next three to four weeks
"Darcy will continue to work closely with our medical and high-performance team as he progresses through his return-to-play timeline."
Moore's injury leaves the Magpies again down on key defensive stocks, with Billy Frampton the only established big man down back.
Jeremy Howe, Brayden Maynard and Isaac Quaynor have all spent time as undersized key defenders and may need to again.
The Magpies have been confident veteran Scott Pendlebury (achilles tightness) will only miss the Brisbane clash.
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