COLLINGWOOD midfielder Adam Treloar will miss round one after scans confirmed he had torn his left hamstring.

The 26-year-old failed to finish the Pies' Marsh Community Series win over Richmond on Sunday – 19 days before the season-opener against the Western Bulldogs.

Given Treloar's history of hamstring injuries, he is expected to take at least the full three-week timeframe for a standard strain.

Treloar missed nine matches at the end of the 2018 home and away season after tearing both hamstrings while sprinting at full pace with the left requiring surgery after tendon damage.

"Adam will work through the regulation 21-day rehab period and then we will re-assess," Collingwood head of football Geoff Walsh said. 

"The strain is mild or low level and the previous major surgery is intact. Adam was confident that the nick was minor and so it is." 

Sent for scans on Monday morning, Treloar said the season opener on March 20 could coincide with the birth of his first child. 

The injury could open the door for fringe midfielders Brayden Sier and Tyler Brown to cement a spot in the round one line-up.