Australia have posted 7-269 at Canterbury, leaving England requiring a record run chase to win the last ODI of the women's Ashes series.
England have been left requiring their highest ever run chase if they are to reach 270 and prevent Australia winning a third straight women's one-day international in the Ashes series at Canterbury.
The total could have been a lot more imposing for the hosts considering Australia were 1-130 when Alyssa Healy was dismissed in the 23rd over, before they ended up with 7-269.
Run-a-ball knocks from Healy (68) and Meg Lanning (69) put Australia in a commanding position before both fell via ugly dismissals to Nat Sciver (3-51).
Healy holed out to Danni Wyatt at deep midwicket for 68 from a half-tracker, the type of ball she clouted to the boundary numerous times in her knock.
Lanning, comfortably looking in the best touch she has this tour, was trying to guide a ball to the legside when she hit a leading edge to Fran Wilson at point.
Sciver completed a triumvirate of big wickets when Ellyse Perry (7) nicked behind attempting a cut shot.
Australia struggled to find any rhythm after this point with Beth Mooney (19) trapped in front by Kate Cross (1-55), Rachael Haynes (12), caught and bowled by Sophie Ecclestone (1-50) and Ashleigh Gardner (29) bowled by Laura Marsh (1-50).
Earlier, Nicole Bolton (4) was unlucky to be given out leg before to Anya Shrubsole when replays showed the ball missing the leg stump (1 for 43).
Jess Jonassen (24) and Delissa Kimmince (18) were the not out batters.
England's previous best chase was 243 against New Zealand in 2008.
England: Heather Knight (c), Amy Jones, Tammy Beaumont, Sarah Taylor, Natalie Sciver, Danni Wyatt, Fran Wilson, Anya Shrubsole, Laura Marsh, Sophie Ecclestone, Kate Cross.
Australia: Meg Lanning (c), Nicole Bolton, Alyssa Healy, Ellyse Perry, Rachael Haynes, Beth Mooney, Ashleigh Gardner, Jess Jonassen, Delissa Kimmince, Georgia Wareham, Megan Schutt.