Collingwood are set to be without Brodie Grundy for close to three months after the Magpies ruckman sustained a knee injury in Monday's win over Essendon.

The 28-year-old suffered the setback late into the Magpies' win, telling Fox Footy postgame he was "pretty sore" but "should be fine".

Despite the two-time All-Australian's initial suggestion, Grundy could miss up to 12 weeks with a PCL injury diagnosed for their star ruckman, who also missed multiple weeks last season with a neck issue.

โ€œWe are all disappointed for Brodie. While he is a key member of our team and will be missed, out of adversity comes opportunity for other members of the squad to play a role during this time,โ€ Collingwood GM of Football, Graham Wright said, via the club's website.

โ€œWe know Brodie will be dedicated to his rehabilitation and will continue to remain involved with the team as he recovers.โ€

The news compounds the Magpies' woes to come from the Round 6 win, with recruit Nathan Kreuger tipped to miss the rest of the season after requiring shoulder surgery.

Grundy has been a pivotal piece in Collingwood's system and enjoyed a strong outing against the Bombers, recording 16 possessions, 33 hit-outs and a goal in the win.