Kane Williamson lamented a "below-par" display across the board as New Zealand slumped to a six-wicket loss against India.
The tourists were thrashed in Dharamsala as India chased down a paltry 190 all out with 101 balls remaining.
Tom Latham made 79 for the Black Caps and Tim Southee's career-best 55 provided the only other bright spot, with New Zealand's Test series whitewash compounded by Sunday's result.
And captain Williamson, himself out for three, was far from happy with how his side kicked off the five-match 50-over series.
"We were below par in all areas, we need to step that up," he admitted. "We're a tough unit, so we need to stick together and have to play our best cricket to beat India.
"We had to weather the storm a little bit, the first 10 overs they bowled really well and we had some soft dismissals.
"It was disappointing with the bat. We lost too many wickets too early.
"India were too good, a very good chasing side and they showed that."
The second match takes place in Delhi on Thursday.