Williamson remains the perfect conduit.
In 13 ODIs since the beginning of last year, he has passed 50 on eight occasions and New Zealand have not lost (seven wins and one tie). It didn't matter when Williamson came in - his entry was spread between the third and 19th overs. In the five other results there was a win (Williamson made 47) and four losses.
On the eight occasions New Zealand have batted first, Williamson has scored 47 or more on seven of them. The exception was a 10 against Pakistan in the opening loss in the United Arab Emirates. His absence raises the question of who replaces him, or at least how the team best compensate if the worst happens during the World Cup.
Opposition teams will seize on such an area of vulnerability. Tom Latham has batted at No3 in the last two games against Sri Lanka for returns of five and 42. Batting cover in the World Cup squad offers few options if Ross Taylor is anchored at No4. Curiously, Latham, who has been touted as a first choice No5 in the optimum World Cup starting XI, is yet to bat there this series. His other appearance came at No4, where he scored 15 filling in for Taylor at Christchurch.
Tim Southee is expected to return today after failing to get a bowl in the washout at Eden Park. He last played the 50-over format against South Africa in October, being rested after the test series in the UAE.
"It's been a good little break. My body's freshened up and I've got over any niggles. I never like missing games but, with the amount of cricket these days, you have to manage the workload. It's a tight schedule and the management of players has been outstanding.
"You can't physically play every game. You need to miss one or two here and there to prolong the periods without injury."
Southee suffered no pain in the nets yesterday after recovering from a minor ankle injury.
He said the flipside to resting was combating the competitiveness among the present pace bowling ranks.
"It comes naturally and the last 18 months have probably seen more competition around training, pushing each other harder and that overflows into the middle."
Kyle Mills joined the squad after returning from a groin injury, meaning the selected 15 for the World Cup are finally assembled together.
Mills took one for 31 from 10 overs in Auckland's victory over Northern Districts and got through training yesterday but he is expected to rest until the fifth ODI against Sri Lanka on Friday. Grant Elliott also trained fully.
The fourth ODI begins at 11am.
3 batting facts
*In 13 ODIs since the beginning of last year, Kane Williamson has passed 50 on eight occasions and New Zealand have not lost (seven wins and one tie). In the five other results there was a win (Williamson made 47) and four losses.
*On the eight occasions New Zealand have batted first with Williamson's presence since the start of last year, he has scored 47 or more in seven of them.
*Tom Latham has batted at No3 in the last two games for returns of five and 42.