New Zealand selectors Wednesday included Fleming in the 14-man squad for the three match Chappell-Hadlee series but said Fleming may miss the first match on December 3 because of an undisclosed "personal medical matter".
Coach John Bracewell was also unable to confirm whether the captain would be available for the remaining two matches on December 7 and 10.
"It's a medical issue, not a cricket one," Bracewell said.
Spin bowler Daniel Vettori would take the captaincy if Fleming cannot play.
"Every cloud may have a silver lining in terms of development of leaders and potential captains within our side," Bracewell said.
Cairns has returned to the side after being dropped for the recent one-day series in South Africa, in which New Zealand was humbled 4-nil.
The 35-year-old, who has retired from Test cricket but hopes to continue in the short version of the game until after the 2007 World Cup, was dropped due to lack of match fitness for South Africa.
But Bracewell said Cairns was ready to step back into the international arena after working on his fitness and playing well at the National Academy at Lincoln, near Christchurch.
"He's bowled with pace, he's bowled with large workloads both into and downwind down at Lincoln. The bowling was our main concern," Bracewell said.
"And he's batted with confidence and aggression."
Fellow all-rounder Jacob Oram, who also struggled for form in Zimbabwe and South Africa after recovering from a back injury, is also showing a welcome return to fitness and form, Bracewell said.
"I'm not really surprised about Jacob, I knew all he had to do was get back on the park," Bracewell said.
Oram picked up a groin injury late in the South African tour, which prevented him from bowling as he completed his recovery from the back injury.
Bracewell said the poor batting form of the team was the most disappointing feature of the South African tour and he was hopeful this would be turned around on home soil.
"We thought we had selected the batsmen in South Africa and we want to continue to show faith in that. Skilled batsmen are good enough to bat themselves out of problems."
The two faces missing from the 15-man one-day squad that went to South Africa are all rounder Andre Adams and spin bowler Jeetan Patel.
New Zealand squad:
Stephen Fleming (captain), Nathan Astle, Lou Vincent, Hamish Marshall, James Marshall, Scott Styris, Craig McMillan, Brendon McCullum, Chris Cairns, Jacob Oram, Daniel Vettori, Kyle Mills, James Franklin, Shane Bond.