Sundar claimed the wickets of New Zealand skipper Tom Latham (28) and Rachin Ravindra, the top-scorer for the visitors in the series so far, for five in a near identical manner as the hosts made the most of the conditions on a track that started turning an hour into the match.
At lunch, Will Young was holding the fort for the visitors, batting on 38 off 73 balls, studded with three boundaries and the lone six of the first session. Daryl Mitchell was keeping him company on 11 runs.
The trick for early success at the Wankhede Stadium is to use the juice on offer in the first hour and cause some damage. After New Zealand opted to bat first, India tried that, and in the absence of Jasprit Bumrah, who sat out as he has not "fully recovered from his viral illness" claimed one wicket.
The hosts had a couple of more opportunities as an edge from Devon Conway off Akash Deep flew in between the third and fourth slips. India, however, managed to claim three wickets in the first session of a match they have to win to avoid series whitewash.
Akash Deep, who moved the ball both ways and extracted puffs of dust on a couple of occasions, made the breakthrough in the fourth over when Conway was trapped in front by a delivery that pitched on the good length and swung in, evading the edge. It also stayed a bit low, which did not help much when Conway opted to review the decision and the decision went against him. New Zealand were 15/1 in the fourth over.
Skipper Latham and Young took the BlackCaps past 50 runs off 84 balls in the 14th over, though they had some moments that kept the Indians quite interested. A top edge off Young, who struck Akash Deep for a couple of boundaries in the 10th over, and a leading edge from Latham's bat fell in the safe zone.
Young showed his attacking instinct by using his feet and carting Ashwin over wide long-on off and swept Sundar to the left of the keeper for a boundary.
Sundar, who was brought in as the second change to replace Akash Deep, struck two quick blows to grab the initiative for India. He first castled Latham with a superb delivery that landed on the off-stump and straightened, evaded the bat, and rearranged the furniture. Latham perished for 28 off 44 balls, hitting three boundaries.
The big breakthrough for India was sending back Rachin Ravindra cheaply as Sundar repeated the delivery that got Latham, sending this one from wider of the crease to spin past the defensive prod to clip the off stump. This was the third time in a row that Ravindra was bowled by Washington Sundar. New Zealand were 72/3 in the 20th over.
Brief scores:
New Zealand 92/3 in 27 overs (Tom Latham 28, Will Young 38 not out; Washington Sundar 2-26, Akash Deep 1-22) against India.