Lock Tom Franklin injured his leg in the opening minutes of the match against Counties-Manukau on Saturday and, although he saw the game out, went to have a scan straight after the game.
It revealed a slight fracture in his lower leg.
His leg is not in a cast but he will not play this Friday night against Manawatu in the last regular-season game.
He may be available for the playoffs depending on his rate of recovery.
Franklin has been in top form this year and his absence will be felt.
Results of the two games yesterday in which Taranaki beat Wellington 54-31 and Bay of Plenty dfeated Manawatu 38-33 mean Otago will host a semifinal.
It will finish either first or second as it shares the lead on 30 points with Wellington.
Franklin’s absence means the side is down to two locks in Blair Tweed and Josh Dickson.
The fourth alternative lock is No8 Paul Grant but he is out with an injured knee.
A player may have to be brought in from Otago B or outside the area.In other games over the weekend, Southland beat Northland 39-31 and Waikato downed Hawkes Bay 46-22.
With the loss, Hawkes Bay was relegated to the Championship next year.