The 2019 World Cup in England is expected to be the toughest yet for bowlers, with small grounds and flat tracks tipped to push the par score in some matches towards 350.

Making it more difficult, Kookaburra balls are used exclusively in one-day cricket as opposed to the Dukes balls, which tend to swing more in English conditions when used in Tests.

"I just looked at some data that out of all the ODI countries, (England) has got the least swing of all over the past 20 years or something," Australia's pace spearhead Pat Cummins said.

"So I'm not really (expecting swing) ... With the brand new ball you still get a little bit (of assistance), just whether it's a bit of extra bounce or maybe a tiny bit of nip.

"I feel like those first three overs is the time to strike. After that it's just that little hard.

"Bouncers we're going to have to use well, that's a real wicket-taking ball."

Australia's Cup preparations ramped up on Wednesday, with their first practice session at the match venue in Bristol ahead of Saturday's opening clash with Afghanistan.

Finalists Australia and New Zealand were among the best exponents of swing bowling on home soil at the last World Cup in 2015, as Mitchell Starc ran through teams with full-pitch bowling.

But the quicks are well aware they'll have their work cut out this time around.

England has proved the most difficult country for ODI bowlers since the last World Cup, with the average run-rate of 6.08 the highest in international cricket.

That's been compounded by the introduction of two new balls for either end in recent years, all but ending any hopes of reverse swing.

Bowlers have also been forced to cop tighter fielding restrictions in the middle overs since 2012, with only four allowed out.

"I don't think you see too many teams running through other teams with big outswingers," Cummins said.

"It's just trying to find a way.

"Definitely some subtle variations, try and bowl some slower balls. Probably bowl them in the middle more than I did in the past and the bouncer.

"Batters are so good, if you give them six balls in the same spot, they're probably going to put them away. You've got to have some options."

Australian Associated Press