Greenwood injured his right ankle during Collingwood's 61-point NAB Challenge loss to the Western Bulldogs at Etihad Stadium on Saturday night.

The 26-year-old was injured when he tackled an opponent in the centre square. The Bulldogs player landed awkwardly on Greenwood's leg, twisting his ankle.

Early speculation had Greenwood likely missing round one, but McGuire's comments on Triple M indicate that the injury is more serious that first thought.

"I think it's going to be a lot longer than round one, I think he'll be out for a fair bit of the early part of the season," he told Triple M. He said Greenwood would have scans to confirm the extent of the injury on Monday.

The former Kangaroo, who was signed by the Pies on a four-year deal, had to be helped from the ground by trainers in considerable pain during the third quarter and could not put any weight on his right leg as he hobbled to the rooms.

The Pies will open their season on April 4 against Brisbane.