Astle was in doubt amid fears his hand was broken when hit by a Marvan Atapattu throw during Tuesday's Twenty20 match, where the 216-match veteran played a key role in New Zealand's five-wicket victory.
But after x-rays confirmed Astle was only bruised, he was confirmed to open the batting with Brendon McCullum as New Zealand and Sri Lanka launch their World Cup buildups in earnest.
The five-match series offers a contest long on incentive but short on form after the performances of both sides during their recent flirtations with the science of Test cricket and the flamboyance of Twenty20.
Both series were tied 1-1, with New Zealand and Sri Lanka taking turns at running hot in one match and cold in the other.
It's this shortcoming which New Zealand coach John Bracewell and Sri Lanka's Tom Moody will be working on as they fine-tune their sides for the World Cup in the West Indies in March.
They are also introducing a rotation policy to avoid burnout, meaning their top sides will not be fielded in every match, with the World Cup the ultimate goal.
With New Zealand resting regular captain and lead run-gatherer Stephen Fleming for the first two games of the series, Astle's clearance solved one problem - providing another aggressive strokemaker against the new ball.
Astle conceded it would have been disappointing to be sidelined, given there was no chance of a run-out when he was hit.
"It would have been a funny way to break a bone. I didn't know he was going to throw it -- I was two metres past the stumps," said Astle.
However, doubts still remain over the fitness of pace bowlers Mark Gillespie and Michael Mason, both with leg injuries and facing last-minute assessments before the match.
"We'll leave it as long as we can," said stand-in captain Daniel Vettori, who already has to contend without injured limited overs specialists Jacob Oram, Kyle Mills, Scott Styris and the rested Shane Bond.
Vettori was understandably anxious for Mason and Gillespie to come through to support left-armer James Franklin after the trio caused Sri Lanka plenty of problems with their pace and bounce in the second Twenty20 encounter.
"It's always been a criticism of subcontinent batsmen when they come to this part of the world -- if you get up to them it unsettles them," he said.
Vettori faced his own batting question marks with an experimental line-up featuring rookies Ross Taylor and James Marshall against an opposition attack featuring Test terrors Muttiah Muralitharan and Lasith Malinga.
"I wouldn't say we're vulnerable, we know it's going to be a big step up," said Vettori, who captains New Zealand for the ninth time in one-dayers.
New Zealand claimed the corresponding series 4-1 last summer, and Vettori said a similarly emphatic margin was needed as World Cup preparations gathered momentum.
"We've talked about if we want to consider ourselves as one of the favourites for the World Cup, we've got to start winning consistently -- and if we're not winning in our own backyard we can't be put up as favourites."
Sri Lankan coach Tom Moody, who presided over a 5-0 drubbing of England in their last series away from home, agreed the series was an important stepping stone to the World Cup, as his side only has four more games in India before heading to the West Indies.
"This is part of the process, another hurdle. It's an important lead-up to our campaign and we want to look at a couple of combinations," said Moody, whose side has the confidence of knowing they beat New Zealand in their last encounter at the Champions Trophy tournament.
New Zealand: Daniel Vettori (capt), Andre Adams, Nathan Astle, James Franklin, Peter Fulton, Mark Gillespie, Hamish Marshall, James Marshall, Michael Mason, Brendon McCullum (wk), Iain O'Brien, Jeetan Patel and Ross Taylor.
Sri Lanka: Mahela Jayawardene (capt), Marvan Atapattu, Malinga Bandara, Tillekaratne Dilshan, Dilhara Fernando, Sanath Jayasuriya, Chamara Kapugedera, Farveez Maharoof, Lasith Malinga, Muttiah Muralitharan, Ruchira Perera, Kumar Sangakkara (wk), Chamara Silva, Upul Tharanga and Chaminda Vaas.