Lock Tom Donnelly, who is due to play his 50th match for Otago this weekend, and No 8 Steven Setephano are both carrying leg injuries and are rated 50-50 chances to play.
Donnelly strained a hamstring at training last week and aggravated the injury in the match against Bay of Plenty in Mt Maunganui.
Setephano badly sprained an ankle in the same match.
It was thought initially he had fractured it, but an X-ray cleared him of any break.
Otago coach Steve Martin said Setephano was 50-50 at best to play this Saturday, as was Donnelly.
Neither player participated at a lengthy training yesterday, much of which was taken up with drills to test ball-handling under pressure and fighting for the ball in the breakdown.
Otago lost its second match in a row, going down to Bay of Plenty on Friday night, with the home side winning 31-20 after getting out to a 24-0 lead at half-time.
Martin said the injuries had handicapped the side in the last 15min of the match.
Paul Grant had been going to come on for Setephano, but the injury to Donnelly forced the coaching team to look at putting Grant in at lock.
Donnelly was able to soldier on and Grant eventually replaced Setephano.
With four games left in the season, and Otago precariously placed in the eighth and final qualifying place for the semifinals, Martin said Otago had to win at least three of those games.
After Tasman in Nelson, it plays Taranaki at Carisbrook, then Waikato away, before the final match, against Wellington at Carisbrook.
Martin said the side lost its way in the first half on Friday night and the Bay of Plenty side took full advantage, having a strong wind at its back.
"We were watching them play rather than going towards them," Martin said.
"They were very aggressive at the breakdown and were releasing some very quick ball. We soaked up a lot of attack but in the end we just ran out of numbers."
Martin said the wind was worth 12 to 15 points.
He said he told the team at half-time to stick to the game plan of gaining territory and the points would come.
Otago did score 20 unanswered points in the second half but a late try from Bay of Plenty first five-eighth Mike Delany was ultimately the difference.
Martin said he was impressed with the performance of reserve flanker Eben Joubert when he came on, and the South African tearaway might get a start against Tasman.
