This heartbreaking news for Broncos fans comes after fellow backrower Kurt Capewell (quadriceps injury) won't be available until Round 20.
Riki is awaiting scans on a potential lisfranc injury via The Courier Mail. There are fears that the injury could rule him out of the remainder of the year after starting every game for the Broncos.
If scans confirm a lisfranc injury, he will be in the same boat as Bulldog Luke Thompson, who has not played since suffering the same injury all season.
The 23-year-old has had a breakout season helping lead the club to the top of the ladder with defending premiers Penrith Panthers.
During his time on the field, Riki has scored five tries, ran 81 metres and made 36.2 tackles per game.
Youngster Brendan Piakura is bound to retake Capewell's spot this weekend, but there has been no confirmation of who will step in due the absence of Riki.
The Broncos will play the Dolphins, which will be a blockbuster clash between the two Queensland clubs on Saturday.