India were the first team in four matches at the tournament to bat first after winning the toss. The other three teams, New Zealand (v West Indies), Bangladesh (against South Africa) and England (v Australia) all bowled first and failed in run chases.
In Sunday's match at Bay Oval in Mount Maunganui, India made a commanding 7-244, then defended their total superbly through the spin bowling of Rajeshwari Gayakwad, Deepti Sharma and Rana as Pakistan were all out for 137 in 43 overs.
Left-armer Gayakwad (4-31 off 10 overs) and offspinners Sharma (1-31) and Rana (2-27) bowled with relentless accuracy to a suffocating off-side field and the Pakistan batters couldn't find profitable scoring areas.
Wicketkeeper Richa Ghosh claimed five dismissals.
Pakistan also bowled well early in the India innings, but a half-century from Smitri Mandhana (52) allowed them to recover to 1-96 in the 22nd over.
India then slumped to 6-114 as Pakistan appeared to grab the upper hand. The wickets that fell included India captain Mithali Raj (9), who in taking the field Sunday, became the first woman and third player after Javed Miandad and Sachin Tendulkar to play at six World Cups after her first in 2000.
Batting at No.7, Vastrakar reached her half-century from 48 balls, as did Rana (53no) to swing the match heavily towards India.
They added 84 runs in the last 10 overs to put a score on the board which required Pakistan to reach their highest World Cup total to win.
"I'm very happy to win my first Player of the Match trophy and in a World Cup game," Vastrakar said.
"I love batting in pressure situations. In domestic cricket, coaches always send me out to bat when the team is under pressure."
India's victory took them to the top of the table on run-rate while South Africa, Australia and the West Indies also have two points.
