The 30-year-old injured his hamstring during the last quarter of Hawthorn's 25-point win over West Coast at the MCG on Friday night.
Guerra underwent scans on Saturday and Hawthorn general manager of football operations Mark Evans said the former Port Adelaide and St Kilda hardman had work to do if he was to play again in 2012.
"Brent's got some work ahead of him to be in a position to play again this season, and the club will explore every option to support and assist him," Evans said.
"Over the next three to four days we'll work on reducing the bleeding in his hamstring.
"Brent's a diligent player and we expect him to make every effort in his rehabilitation."
Guerra, who grabbed high on his left hamstring after the tear, is expected to miss at least four weeks.
He believes he is still a chance to return."Definitely (a chance), I've just got to be positive about it. Hopefully all goes well and the boys can have a few wins," Guerra told reporters.