They are likely to make the semi-finals if they win their last three, starting with the hosts (22:00 GMT Saturday).

"If we can handle this and get through this, it will show what we're capable of," Brunt told BBC Sport.

"We're really up for it - we just want to get stuck in.

"We're out here to put on a performance and hopefully that is what tomorrow will be."

England were winless through the preceding Ashes series with Australia, then suffered World Cup defeats by Australia, West Indies and South Africa.

They would probably have been eliminated had they lost a fourth game, only to bowl India out for 134 and then chase the target with almost 19 overs to spare.

The hosts find themselves in a similar do-or-die situation, with the biggest crowd of the tournament so far expected at the historic Eden Park in Auckland, New Zealand's national stadium.

"I feel quite calm," said 36-year-old Brunt, England's all-time leading wicket-taker. "It's also a must-win game for them.

"We're getting better and better each game and we hope to continue on that path."

Brunt has managed to take only one wicket in the World Cup so far, often struggling with her length.

Speaking on the No Balls podcast, former men's captain Nasser Hussain said England's attack must collectively look to bowl fuller.

"If you look at the tournament so far, the people who have pitched it up have got the wickets," said Hussain, who led England between 1999 and 2003.

"England are still in this, they could easily go on a run."

Brunt admitted to a struggle for form, saying it was a "sore subject", but also explained England are dealing with "unknown territory" on what is their longest ever tour.

They arrived in Australia for the Ashes in early January and are approaching three months away from home.

"We've been away a long time," said Brunt. "Things are different than they normally are and we've had to figure that out.

"We're learning a lot about ourselves. It's tough mentally and emotionally."