Kane Williamson has suffered an "undisplaced fracture" to his left thumb, New Zealand Cricket said on Saturday, a day after Williamson's left hand was hit by a throw while he was completing a run in the game against Bangladesh in Chennai.
An X-ray confirmed the injury, with NZC saying Williamson will remain with the squad "with the aim of being available for the back end of pool play next month". Wicketkeeper-batter Tom Blundell will be flown in to India as cover, although he will not be officially part of the squad as of now.
"Firstly, we're all feeling for Kane to have this occur after all his hard work to return from his knee injury," head coach Gary Stead said. "While it's disappointing news, the initial diagnosis has given us some optimism he can still feature later in the pool play following a period of rest and rehabilitation.
"Kane is clearly a massive part of our side, and a world-class player and captain - so we'll look to give him every opportunity we can to return in the tournament."
Williamson's thumb and wrist were initially bandaged by the physio just after he was hit at the start of the 38th over of New Zealand's chase against Bangladesh. But then he retired hurt in the 39th over with New Zealand not far from their target, which they achieved with 43 balls remaining for an eight-wicket win - their third in a row at the World Cup.
The game against Bangladesh was Williamson's return to international action after suffering an ACL tear during the IPL opener in late March this year. He was away from cricket for close to six months, and only returned to action in the two warm-up games ahead of the World Cup, where he scored 54* and 37 against Pakistan and South Africa, respectively.
Williamson was included in New Zealand's World Cup squad despite still being in the recovery stage. He had earlier travelled and trained with the side in England in the lead-up to the World Cup.
"[It needed] a little bit of icing afterwards, but it's all part of the process," Williamson had said after his half-century in the warm-up against Pakistan. "Yeah, it [playing the World Cup] wasn't a reality certainly five months ago and [I've] been quite fortunate with some of that recovery, and to be named in the squad is really exciting for me... It was nice to do that today."
Despite Williamson having missed New Zealand's first two matches of the World Cup - against England and Netherlands - New Zealand went on to win both games convincingly under the leadership of Tom Latham. New Zealand next play Afghanistan - also in Chennai - on October 18, with Latham likely to stand in as captain again.