The Three Lions are due to face the Western Australia President's XI at the WACA tomorrow in the first of their tests prior to the winter series against Australia, but Cook and Broad are not being risked due to their back injuries, while Pietersen is being given time off following a hectic schedule.
Wicketkeeper Matt Prior will skipper the side in the absence of the three men, and has instantly played down any worries regarding their fitness.
"Cookie has a stiff back but rushing him into something is probably not the best idea," Prior told Sky Sports News. "Him missing this game is purely precautionary, so I'd be very surprised if he doesn't play the next one.
"KP has jetted around the world and just needs a little bit of rest and recuperation, so he can get into the right time zone, at the very least.
"Giving him a few more days is the best preparation for him."
The Ashes gets underway on November 20 in Brisbane.