BRISBANE defender Daniel Rich has ruptured a ligament at the front of his left ankle and will be out for an indefinite period.

Rich suffered the injury in the opening quarter of Saturday's loss to St Kilda and scans on Monday revealed the news.

Rich will miss Saturday's match against Melbourne at the Gabba and will then be assessed on a "week-to-week" basis, a club statement said. 

The 27-year-old is fresh off one of the best seasons in his nine-year career, playing all 22 matches and averaging 21 disposals, playing largely at half-back.