Women's Ashes - Key battles: Haynes v Knight, Perry v Sciver and the battle of the seamers

Australia and England go head to head in the 2017 Women's Ashes, starting on Sunday - but what are the key battles ahead of the multi-format series?

Australia hold the Ashes after their 10-6 win in 2015, but they face a tough test to retain them against this summer's ICC Women's World Cup winners England, who are ranked No 1 in the world.

Here, we assess which showdowns will decide the fate of the Women's Ashes...

Rachael Haynes v Heather Knight - The Captains

Two Ashes newcomers in terms of captaincy and how they both cope under the pressure of an Ashes series could go a long way to deciding who takes the spoils.

Knight replaced Charlotte Edwards in 2016 and last summer led England to glory in her first Women's Cricket World Cup as captain on home soil, so her tactical nous has been tested under intense pressure.

Haynes replaces the injured Meg Lanning as skipper and the decision surprised a few with the Aussie selectors overlooking Australia vice-captain, New South Wales and Sydney Thunder captain Alex Blackwell.

The 30-year-old took charge twice at the recent World Cup when Lanning was being rested, claiming two wins, but her credentials for the top job will certainly be tested again under the microscope of an Ashes series.

Nicole Bolton and Elyse Villani v Tammy Beaumont and Sarah Taylor - The Power Hitters

What a year it's been for Beaumont, who was named player of the tournament at the World Cup after finishing as the top run scorer.

The 26-year-old, who won the Cricket Writers' Club Women's Cricket award, hit an impressive 410 runs in nine matches at an average of 45.55 and a strike rate of 76.92.

And with Taylor, who scored 396 runs at a strike rate of 99, coming in at number three, England have the power at the top of the order to take a game away from any side - as they proved by smashing England's highest one-day international partnership of 275 in the World Cup against South Africa.

Australia will have to fight fire with fire at the top of the order and it will fall to Bolton (351 runs at an average of 50.15 at the World Cup) and Villani ( 148 runs at a strike rate of 112.97), who both possess clean ball-striking power to trouble the England bowlers.

Ellyse Perry v Natalie Sciver - All-rounders

Everyone knows about the star quality of Perry, who has been player of the series for the last two Ashes contests.

She comes into the series off the back of a brilliant World Cup, scoring 406 runs and taking nine wickets and she'll once again be a key component of Australia's side.

England's all-round contribution comes from Sciver, who has also been in great form this year, playing a key role with bat and ball in England's triumphant World Cup campaign before leading the Surrey Stars to their first Kia Super League Finals Day.

The 25-year-old, whose form was recognised by her peers after she named PCA Women's player of the Year, has been billed as the women's side's equivalent of Ben Stokes by coach Mark Robinson, showing her importance to the team with bat and ball.

Megan Schutt and Lauren Cheatle v Anya Shrubsole and Katherine Brunt - Battle of the Seamers

"England's best chance of winning this series is through their bowling attack - Anya Shrubsole, Katherine Brunt and their young spinner Sophie Ecclestone are going to be crucial to England regaining the Ashes."

That's the verdict of none other than former England captain Charlotte Edwards, who has highlighted the importance of Shrubsole and Brunt to Knight's side's chances of victory down under.

Shrubsole, who bowled England to victory in the World Cup final with figures of 6-46 is ranked seventh in the ODI bowling rankings, while Brunt is fifth and how quickly they adapt to Australian conditions could play a key part in the series.

For Australia, Schutt will lead the attack alongside Perry but Cheatle, who returns to the squad following a six-month injury lay-off, could fill the other seam bowling berth.

Cheatle burst onto the international scene in 2016 to earn place in Australia's preliminary World Cup squad, only to be ruled through injury, so the left-arm quick will be looking to make up for lost time against England's powerful top order.