New Zealand opener Devon Conway has been ruled out of the first Test against Australia at the Cello Basin Reserve in Wellington due to a thumb injury.

"The decision to rule Conway out was made following additional scans in Wellington yesterday which revealed damage to his left thumb," the New Zealand Cricket said in a statement.

"Another update will be provided later in the week following further medical consultation to ascertain the extent of the injury and the final diagnosis," it added.

Australia are set to play a two-match Test series against New Zealand in the trans-Tasman cricket rivalry after sweeping the three-match T20I series 3-0.

Conway suffered the injury during the second T20I against Australia in Auckland while wicketkeeping and did not keep wickets or bat in the match further. He was ruled out of the final T20I of the series.

New Zealand head coach Gary Stead said Conway is a class player and was looking forward to the series.

"It's disappointing for Devon to be ruled out on the eve of an important match. He's a class player batting at the top of the order for us and I know he was really looking forward to this series," he said.

Kiwis have named Henry Nicholls as Conway's cover in the squad and the Canterbury batter will join the team in Wellington for training this morning.

New Zealand had also been sweating on the fitness of Rachin Ravindra after the all-rounder experienced soreness in his left knee and sat out the final T20I but Stead confirmed that the 24-year-old rising star would in fact be available to take the field at Basin Reserve.