Opener Martin Guptill will be under scrutiny again before New Zealand's next test series in August.

Another test cricket series against Australia, another question mark hanging over Black Caps opener Martin Guptill.

New Zealand's top-five batting was identified by coach Mike Hesson as the major must improve after the 2-0 home series defeat to Australia, as they switch focus to the World Twenty20 in India next month.

No-one will be more relieved than Guptill at the change to white ball cricket. The opener was unstoppable in limited overs matches at home but in four test innings against Australia scored 81 runs at 20.25. He wasn't the only one to struggle, but questions continue over Guptill's ability against quality fast bowling as he ended the five trans-Tasman tests with 163 runs at 16.3.

The Black Caps' next test series isn't till August when they play two tests each in Zimbabwe and South Africa. Hesson confirmed Guptill wouldn't be considered to drop down the order following Brendon McCullum's retirement and admitted he needed to improve.

READ MORE:

* Aussies fume at crowd abuse

* Fitzsimons: Smith fails test

* Southee under microscope

"Three tests ago, Martin got a very important hundred for us [against Sri Lanka in Dunedin]. Martin still hasn't quite nailed it at test level but again we think he has some good qualities. No doubt we need to tweak a few things but we still have a lot of confidence in Martin," Hesson said.

With McCullum gone, Henry Nicholls looks most likely to slot in at No 5 in tests with the injured Ross Taylor returning. "Henry is a fine player. He showed that at the Basin [Reserve]."

The batting numbers told the story of the series.

Four of Australia's top-five, Joe Burns, Usman Khawaja, Steve Smith and Adam Voges, averaged 70 or better while the Black Caps made grim reading. McCullum's blistering 145 on Saturday saw him average 45 in four innings, while Kane Williamson (35.5), Tom Latham (28) and Nicholls (19) didn't post the numbers their team needed.

Taylor's absence was a factor but not a major one, Hesson said.

"The top five of Australia outplayed us and Ross is an experienced player and no doubt would have made a contribution in these two tests. It would be glossing over a few things if we felt one player would make a difference," Hesson said.

Latham (Kent), Williamson (Yorkshire), Taylor (Sussex) and the injured Mitchell Santner (Worcestershire) all join English counties during the Black Caps' winter break.

When New Zealand reassemble in August they have a heavy test schedule with tours to Zimbabwe (two tests), South Africa (two) and India (three in October), then home tests against Pakistan (two), Bangladesh (two) and South Africa (three) next season.

The Black Caps are ranked sixth in tests to Australia's one, and beating teams ranked above them continues to be a problem. Under McCullum, New Zealand won three of 19 tests against the current top-five.

WISH LIST

South Africa and India will again provide a good form-line in tough foreign conditions where bounce then spin will have to be combated. Hesson's wish list is simple.

"I think the top-five making big scores. We have got quite a few starts in this series but have been put under pressure by the moving ball. When it's reversing it tends to swing later and swing both ways so that challenges you.

"From a bowling point of view we are going to have to create more opportunities on flat wickets. We have done it before but Australia's top-five were able to combat that in these two tests."

Hesson said the pace bowling would create some headaches with selection. Tim Southee was well below his best after returning from a foot injury, and Matt Henry was thrown the second new ball. Neil Wagner leapt up the pecking order with his seven-wicket haul in Christchurch based around a bouncer barrage. Mastering reverse swing would be one key work-on for all.

"Tim and Trent [Boult] for two years have been exceptional for us but we have different guys in the squad who do different things. We have alluded to Neil. He brings a different option. Doug Bracewell is a bit different, as is Matt Henry, so within those five we have got, we should be able to get a pretty good attack in all conditions around the world."