Ashes 2013: England top order must deliver - Alastair Cook

England's batsmen must find their form if the team are to retain the Ashes in Australia, says captain Alastair Cook.

Openers Cook and Joe Root plus number three Jonathan Trott struggled as the hosts relied heavily on their bowlers to secure a 3-0 victory in the summer.

"Top-order runs are vitally important down under," said Cook. "400 is the bare minimum to get in the game, so that is the job of the top order."

England arrive in Australia on Friday with the first Test on 21 November.

They beat their hosts 3-1 in 2010-11 - their first triumph down under for 24 years - and followed up with victory on home soil in July and August this year.

Cook's men are seeking to become the first England side since 1890 to win four Ashes series in a row and the Essex batsman accepts his team are rightly regarded as favourites to beat Australia, who have lost seven of their past nine Tests.

"I think that's a fair comment when you win the last three series, but I don't think it makes much difference," the 28-year-old said.

"I thought we coped with [being favourites] pretty well last summer. But if you look at Australia as a whole, not many sides win there so it is no mean feat.

"That is the challenge. We know what we have got to do. Score big first-innings runs and apply pressure with the ball."

Cook went past 50 on just two occasions this summer, but failed to compile a century and ended up scoring 277 runs at an average of 27.7.

However, he has fond memories of his previous Ashes series down under, when he scored 766 runs at an average of 127.67.

"I didn't execute as well as I could have done this summer," he said.

"I had a good time there last time. It would be great to repeat some of those feats.

"I enjoy batting in those conditions. The ball can be flying past your ears. It's a real test of the skills you need against fast bowling."

England will play warm-up matches in Perth, Hobart and Sydney before the first of the five-match Test series in Brisbane.

"The games are important for us to get used to conditions," said Cook. "Ideally all the batters will get some time in the middle and the bowlers will get some miles in their legs. That's the ideal scenario."

Kevin Pietersen will fly out to Australia 48 hours later than the rest of the squad after being granted compassionate leave.

It is understood the batsman has been given the dispensation following the death of a friend.

The 33-year-old is expected to be available for England's first warm-up game against Western Australia in Perth, which begins on 31 October.