The Volts are in second place with 26 points from seven matches but need to beat Canterbury in Queenstown later this week to help close the gap on competition leader Northern Districts, which is 10 points clear.
But they will have to chase that victory without classy opening batsman Aaron Redmond, pace bowler James McMillan and experienced seamer Warren McSkimming.
Left-arm strike bowler Neil Wagner is also under an injury cloud with back and hip complaints.
Redmond has spent most of the summer on the sideline recovering from a groin strain he sustained while bowling in a twenty/20 international against Pakistan in Abu Dhabi in November.
He scored a century in his comeback first-class game but looks to have re-aggravated the injury while batting during Otago's dramatic 24-run win against Auckland last week and has been ruled out.
Otago A coach Mark Bracewell, who is helping hold the fort while Volts coach Mike Hesson is away on national duty, said it was too early to say whether Redmond's injury was a recurrence of the groin strain.
"He was having a scan and the results take about three days," Bracewell said.
"But it is the same sort of injury which kept him out . . . and to him it feels the same.
"But he is not that certain what it is yet."
Darren Broom will replace Redmond in the squad and will be making his first-class debut.
Broom made a great start to the summer for his club side, North East Valley.
But in eight one-day matches for Otago he has scored 149 runs at a modest average of 24.83.
He produced his best form, though, in Otago's last one-dayer, scoring 73 against Central Districts.
McMillan has had a dreadful run of injuries throughout his career.
He shortened his run-up two years ago to help curb his susceptibility to injuries, but he has been ruled out with an abdominal strain.
McMillan's misfortune has paved the way for James Fuller, who comes into the Otago team for the first time.
"James was a New Zealand under-19 bowler last year and impressed on their internal tour.
"He is a right-arm quick and also a very useful batsman.
"He's a very exciting prospect.
"He has a beautiful rhythmic action and generates a lot of pace.
"He would be as quick as anyone around here."
McSkimming missed Otago's last match after injuring his back while playing in Invercargill late last month.
He looked to be running freely at practice yesterday, but with three rounds remaining Otago has decided to give its most experienced bowler another week and keep him fresh for what could be a crucial game against Northern Districts in Whangarei later this month.
"If we play him now and lose him for the next two we are up the creek.
"It is better to be patient and wait for him to get his bowling loads up," Bracewell said.
Wagner has been struggling with hip and back niggles and will have a bowl in the nets today.
"We'll know more then," he said.
