He puts his great success of the past year down to the increasing confidence that comes with experience at the highest level.
"I'm 20-something tests in now. I've been trying to learn from each innings, keeping it really simple and making more meaningful contributions."
Nicholls will be part of a Black Caps batting line-up for these ODIs which has only three of the top seven from the test series win over Sri Lanka. His middle order colleagues, Kane Williamson and Ross Taylor, are the only other specialist batsmen to move from the red-ball game to the white-ball matches.
Hamilton wicketkeeper-batsman Tim Seifert, who made a sparkling 55 for the Northern Knights against the Central Stages in the Super Smash T20 match at Bay Oval last Thursday night, comes in as a wicketkeeper-batsman while the prolific run machine of the past two weeks Tom Latham, is rested.
Martin Guptill returns after injury ruled him out of the white-ball matches in the UAE and he's likely to go in first with the electric Colin Munro in an opening partnership that has the potential to be both fruitful and spectacular.
With the World Cup in England only six months away, the battle for the all-rounders positions in the squad intensifies in the next few weeks too.
Colin de Grandhomme, who's played every Black Caps test, ODI and T20 International in the last two months, is the incumbent but is now being stood down to recover from his hectic schedule of 11 matches across three formats since the start of November.
That gives Doug Bracewell and Jimmy Neesham the chance to impress against Sri Lanka after both were promoted from the New Zealand A team.
"Jimmy and Doug will both get opportunities in that role," according to Black Caps coach Gary Stead.
"There are still World Cup places up for grabs and we'll be looking closely at how the all-rounders go in these matches. It's the consistency from all of those players that we're looking for."
Stead also has his eye on the team's fielding.
"I'd like in this white-ball series, and we've got it for the next couple of months, to really focus hard on that and being one of the best fielding teams in the world."
The coach sees these matches, and the ODIs to come against India and Bangladesh, as a vital part of World Cup planning.
"It's about being clear on the game plans we want to use, and making sure that we're playing to the roles we want to get people in.
"We know at the World Cup scores are often going to be 300 plus, and I want to make sure we get our heads around that as well."
Both the Black Caps and Sri Lanka will be training at Bay Oval today .