When Williamson suffered the injury in April he was viewed as only a very slim chance of making the World Cup, but his progress in recent weeks has been encouraging and he will be given every opportunity to prove he is ready.

The 15-player squads need to be submitted to the ICC by September 5 but can be changed without approval up to September 28.

"[We've] got about two weeks from now until we name that side," New Zealand head coach Gary Stead said. "Going to give him every chance and use that full amount of time.

"He's in full rehab mode, he's back batting in the nets again which is great to see. He's progressing really well but again there's a lot of work for him still to do to make sure he gets to where we need him to be."

It could be that Williamson will be included even if he won't be ready for the early matches in the World Cup, or another option could be to have him as one of the travelling reserves although there would then need to be an injury in the original squad for him to be brought in. There will also be longer-term considerations taken into account.

"They are all the things we are weighing up right now," Stead said. "There's a chance that even if Kane was named that he wouldn't be available right at the start of the tournament. But he also might be, and he also might not be ready.

"It's still a little bit of crystal-ball gazing [about] where he will be at. Yes, of course, we want him at the World Cup but there is that bigger picture in mind that we want Kane Williamson fit for the rest of his career.

"They'll be honest conversations that Kane and I will have with each other around exactly where he is at, to make sure we get the best outcome for our team but also the best outcome for Kane Williamson and his long-term career."

"The birth of a child is a special time and we are a family environment," Stead said. "We are glad to be able to support Jimmy in heading home."