Ben Stokes has promised England will not go down without a fight despite a heavy defeat to Australia, insisting "this is our World Cup".

The world number ones and tournament hosts have suffered three losses in six group games, outgunned by Pakistan, shocked by Sri Lanka and now bested by their oldest rivals for just the second time in the past 12 one-day internationals.

Having entered the tournament as heavy favourites this was the not the script England expected to follow, and they now face a pair of potentially critical matches against India and New Zealand.

Stokes has done more than most to avert the last two results, anchoring a pair of doomed chases with scores of 82 not out and 89, and he is not likely to ease off now.

Asked if he had a message for the fans, the all-rounder said: "This is our World Cup.

"We've had great support over the last four years and we know how much a World Cup means to fans. We know that as players as well. We're not going to take a backward step. This is our World Cup."

Stokes was at a loss to explain why his side have buckled under pressure after two years of increasingly polished performances in the 50-over game.

What he is sure about is the need to avert panic.

"Back to back losses can sometimes make you think differently as a team, but we're not going to go back on our method of playing," he said.

"We're not for a minute going to take a backward step. We're a very, very confident team, these last two games aren't going to change that."

Stokes received treatment on both legs during his innings but said his fitness was nothing to worry about.

"It wasn't cramp, it was just tight calves," he said.

"I suffer with it every now and then, especially on muggy days like this. There's nothing to worry about."