Black Caps opening batsman Devon Conway has been ruled out of the first Test against Australia with a thumb injury, New Zealand Cricket said Wednesday on the eve of the game.

Conway will miss the match, starting in Wellington on Thursday, after hurting his thumb in a Twenty20 defeat to Australia last Friday in Auckland. New Zealand went on to lose the T20 series 3-0.

He has been sidelined for the first Test after scans showed damage to his left thumb, New Zealand Cricket said. Experienced batsman Henry Nicholls has been called up as cover.

"It's disappointing for Devon to be ruled out on the eve of an important match," said New Zealand head coach Gary Stead.

"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."

But Stead welcomed the return of Nicholls, who was originally left out of the squad.

"It's nice to have a player of Henry's calibre to call on," Stead said.

"He has plenty of Test experience and covers a number of positions in our batting order."

The Black Caps are waiting to know whether Conway will be able to play in the second and final Test, which starts in Christchurch on March 8.