Devon Conway is a solid incumbent in the other but recent struggles may have opened the door for Tim Seifert, while Rachin Ravindra’s recall for the game-five defeat confirms he remains in the frame.
The pair put on a record fourth-wicket unbeaten stand of 139 at Hagley Oval, helping the hosts complete a quartet of impressive victories.
In the T20 format, only two Black Caps batting duos have been more productive than Mitchell and Phillips, who average 46.1 in 16 innings together. For pairs with at least 10 innings, Phillips and Conway average 59 from 15, while Williamson and Martin Guptill combined for 47.9 from 30.
They didn’t add to that tally on Sunday, with Mitchell resting as the Black Caps slumped to a sloppy defeat, but already loom as a match-winning union ahead of the World Cup in June.
Phillips is typically the more aggressive player but largely ceded that role to Mitchell in the fourth match, lavishing praise on a batter whose T20 prowess is approaching his world-beating abilities in both longer forms.
“He’s fantastic,” Phillips said. “Just the calmness that he’s got out there, he shows a level of intent that not many guys have. Every ball is an absolute competition for him.
“He believes he’s born for those sorts of situations and he proves it time and time again. He’s absolutely awesome to bat with.
“It wasn’t the usual type of innings I play, and I understood that, but it was what the team required and you’ve got to be adaptable and change to situations out there.
“That’s what I enjoy so much about being in the middle order.”
Mitchell, too, enjoys his role in the powerful one-two punch, his reserved nature contrasting and combining well with the ebullient Phillips.
“It’s always fun winning games of cricket for your country, and to do it with GP,” Mitchell said. “We’ve played a lot of cricket - especially T20 cricket - with each other now and the way he goes about his business, I love watching him do it at the other end.
“He’s a special character, he always finds the fun in things, and that’s what I love about him. We’re just out there doing what we can for the country and trying to get stuck in.”
That approach served the Black Caps well against Pakistan, before an understrength side crumbled in the finale. With a plumb three-game series against Australia coming in February, and with the World Cup creeping closer into view, Mitchell has liked what he’s recently seen.
“You take the outcome out of it and the way we’re playing cricket at the moment, especially in T20s, we’re really proud of how we’re going about our business,” he said.
“We’ve obviously got that bigger picture of what’s coming up in a few months’ time with the World Cup. It’s about staying true to how we want to play as Black Caps and being really clear on that, and hopefully that means outcomes like winning games of cricket.”