The amazing numbers behind Khawaja's form

The moment Usman Khawaja stopped fearing for his place in Australia's Test side doubled as the catalyst for a golden run.

Khawaja, whose knock of 140 in Wellington came after Australia were in trouble at 2-5, was reluctant to nominate a single factor when asked about his recent form.

However, the classy left-hander noted confidence was key on Saturday.

Khawaja didn't criticise former coach Mickey Arthur and captain Michael Clarke, who famously punished him in India three years ago for not submitting 'homework'.

But the 29-year-old made it clear just how relaxed the group is compared to his previous ill-fated stints in the national side.

Khawaja said having confidence and security in his spot in the side had been a massive influence.

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"As a cricketer, as a sportsman you don't ever want to be in a position where you're feeling (that) pressure, there's enough pressure going on so when I got that first hundred it meant a lot, just for myself," Khawaja told Optus Sport's Across the Ditch.

"I always knew in my heart I was good enough for Test cricket but there's a difference between knowing it and doing it so when I'd actually done it, it was a big weight off my shoulders.

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"And in all honesty, even in that first game I was making sure that I was just enjoying it, whether I failed or whether I succeeded I was going to make sure that the third time round that I was going to enjoy it.

"(Because) it doesn't last forever and that's what I'm doing right now, just really having fun playing cricket no matter what form it is or no matter who I'm playing for."

Khawaja's first nine Tests were spread out over five series, he averaged 25 and was often waiting for the axe to fall.

Since being recalled for the opening Test of 2015-16, Khawaja has posted four tons and averaged 128.80 from five games.

Khawaja's purple patch in Test side

• 644 runs at an average of 128.80 from five games
• Has been dismissed once for less than 100, when he scored 56 in second innings at MCG
• Four centuries, three of them coming against New Zealand
• Also scored two Twenty20 tons for Sydney Thunder in the KFC Big Bash League

How it compares to previous Tests

• 377 runs at an average of 25.13 from nine games
• Only passed 50 twice
• Zero centuries, with a high score of 65
• Was dropped after fourth Test of the 2013 Ashes and didn't play for Australia again until last November

Now compare it with Steve Smith's magnificent 2014-15 season

• 769 runs at an average of 128.16 from four games
• Broke the record for most runs in a Test series between India and Australia
• Scored a ton in the first innings of every match, three of them as captain