Captain Eoin Morgan’s team are seeking a sixth successive ODI series win and ninth in their last 10 attempts dating back more than two years.
Such has been their improvement since the last World Cup, though, they have rarely faced a must-win fixture in that time – and in fact when they did, in last summer’s Champions Trophy semi-final, they fluffed their lines against eventual tournament winners Pakistan in Cardiff.
Bairstow therefore rightly identifies tonight’s match at Hagley Oval as an indicator of England’s progression towards their home World Cup campaign in 2019, when they will need knockout successes at some stage.
Asked if that was the case, he said: “Absolutely – it’s huge.”
England have got themselves into a tight spot after squandering the ‘open-goal’ position Bairstow and Joe Root’s centuries put them in to seal the series there and then at Dunedin’s University Oval.
The Yorkshire pair powered England to 267-1 in the 38th over, and the brink of an unassailable 3-1 lead – only for a collapse of six wickets for 21 runs and then Ross Taylor’s brilliant 181 not out to turn the match around.
Bairstow nonetheless remains confident about their prospects against the Black Caps.
“The way the guys reacted to situations over the last two ODI series helps,” he said.
“You can look back at the way we closed it out (to clinch the series against Australia) in Sydney and in Wellington when the guys have been asked to stand up.”
Bairstow and Root have been scoring centuries together since they were in short trousers – and delivered again in Dunedin.
Before Wednesday, Root had gone 16 ODI innings without a century, dating back to last June, while Bairstow passed 50 just once in his eight most recent attempts.
But the two batsmen, who first met as Yorkshire schoolboys 15 years ago, were back on song with a second-wicket stand of 190 at the University Oval.
Bairstow was hardly panicking about his recent form.
“I didn’t get a big one against Australia, but it’s been threatening,” he said. “It’s the nature of opening the batting.
“You will nick off, they are allowed to bowl good balls, it swings, the pitch is fresh – so when you do get in it’s important to make it count.”
Asked about the run-making habit he and Root formed all those years ago, Bairstow confirmed an instinctive understanding has long been in place.
“We have known each other since we were 13. When we get together and are batting it just all clicks.
“(They first met) at the indoor school at Headingley – on a scholarship programme at Yorkshire. We were both tiny tots back then.
“It’s been a great journey so far, and there are a lot more memories to come playing together.”
Bairstow is confident the rest of England’s powerhouse batting line-up will soon be back on track too.
“We are a fast learning team,” he said.
““You don’t put a string of results together like we have before, and change the way we play so quickly, if you’re not fast learners and fast adaptors.
“The World Cup’s not tomorrow or in two days – it’s in 16 months.
“This is part of the journey – it’s about getting it right for when that comes around.”