His absence has highlighted his value.
While Brendon McCullum is capable of unsettling opposition with cavalier strikes as an opener, his century in Hamilton revealed an inconvenient truth: batsmen rarely win matches single-handed.
In Christchurch McCullum's record-equaling quickest half century bought New Zealand time in the chase for 219 but his effort required consolidation from Corey Anderson with 81 from 96 balls.
New Zealand need middle order resin to maintain the innings tempo either defensively, if McCullum and Martin Guptill exit cheaply, or with an attacking mindset if a platform has been set.
Williamson remains the perfect conduit.
In 13 ODIs since the start 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 No.3 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 No.4. Curiously, Latham, who has been touted as a first choice No.5 in the optimum World Cup starting XI, is yet to play there this series. His other appearance came at No.4 when 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. He was 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 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's expected to rest until the fifth ODI against Sri Lanka on Friday. Grant Elliott also trained fully.
Southee said the Saxton Oval pitch was "a touch slow last year" but this time around he'd heard reports there was more pace and bounce.
The fourth ODI starts at 11am.
- By Andrew Alderson of the Herald on Sunday in Nelson
