"We've got a big series against Pakistan, then we look ahead to the Australian one-dayers a few days after that.
"Pakistan are a very strong team, and showed glimpses of that at the Basin [last Monday], so we want to be on top of our game on Sunday."
Mascarenhas also confirmed he is stepping down from the job at the end of the Australian tour to spend more time with his family in Melbourne.
The former England allrounder began working with New Zealand last March and insisted family reasons were the only issue around his decision.
"It's been really tough being on the road a long time.
"I think it's the right thing to go home and spend more time with them."
His decision had been made only recently and wasn't easy as he'd had "an amazing time and it's been a great job".
Mascarenhas insisted he had strong relationships with the players and fellow staff.
New Zealand Cricket is embarking on a search for Mascarenhas' replacement. New Zealand's next assignment is a tour to Zimbabwe and South Africa in August.
As for tomorrow, regular skipper Brendon McCullum is expected to return after being absent since injuring his back colliding with advertising hoardings at Hagley Oval against Sri Lanka on December 28.
Coach Mike Hesson was adamant a few weeks ago, before the injury, that while McCullum might miss the odd game over the home summer, whenever he played, he would lead.
There would be no playing under the skipper-in-waiting Kane Williamson, who has been in charge in McCullum's absence.
BJ Watling, who missed out in the Napier rain, will get a rare chance tomorrow, replacing regular short-form wicketkeeper Luke Ronchi, who is sorely out of form with the bat - just one score above eight in his last eight ODI innings.
New Zealand's ODI squad to play Australia is expected to be named this morning, making performances tomorrow irrelevant in that context.
Pakistan gave New Zealand's batsmen a serious hurry-up in the opening game in Wellington before the lower order wagged hard, lifting the team from 99 for six to 280.
Lefthander Henry Nicholls announced himself with a fine 80, and Mitchell Santner and seamers Matt Henry and Mitch McClenaghan did what fast bowlers love doing and swung hard and well - until McClenaghan was clunked a nasty blow above an eye which required surgery yesterday.
New Zealand's superior familiarity with Eden Park's geographic peculiarities should stand them in good stead tomorrow.
That said, Pakistan were well worth their 16-run T20 win on the ground a fortnight ago.
The boundaries square of the wicket can be deceiving to batsmen eyeing the crowd, especially considering the substantial difference with the lengths to clear the straight hit boundary.
"We know we don't want to be pitching it up in the [batsman's] arc too often," Mascarenhas said.
"We'll look at other ways to get people out."
The Black Caps match against Pakistan will start at 11am.