The star all-rounder has bowled only five overs - during the recent Champions Trophy in India - for his country since ankle surgery last July.
Flintoff has said since the team's arrival in Australia last weekend he is fit to bowl but team coach Duncan Fletcher is unsure whether the England skipper can bowl the long spells needed for Test cricket.
The much-anticipated Ashes battle gets underway at Brisbane's Gabba ground on Nov 23, with England out to retain the urn they wrestled off Australia in last year's unforgettable series in England.
Fletcher, the architect of England's euphoric 2-1 series triumph, admitted Tuesday he was unsure how many overs Flintoff could get through at the Gabba.
Amid those doubts the tourists are expected to choose four other bowlers as insurance, which means that one of three batsmen, Alastair Cook, Ian Bell or Paul Collingwood will miss out.
"We've got to look at five bowlers, especially now with Flintoff, with the workload he takes on," Fletcher told reporters here Tuesday.
"If we were confident of him getting through a lot of overs we could probably look at (playing) four (bowlers), but with Flintoff not bowling many, we've got to go in with five bowlers."
England's major concern with playing five bowlers is carrying a long tail, as wicketkeepers Geraint Jones and Chris Read average 26 and 20 with the bat respectively, and would go in at No.7.
Ashley Giles is the only England bowler who has a healthy batting average (21), and that may be crucial in his fight for selection against fellow spinner Monty Panesar (10).
Fletcher said the length and strength of the tail was something that needed addressing.
"That's the thing we've really got to look at in the next couple of games we play in," he said.
The competition for places means England must use their three warm-up matches astutely.
Fletcher said the players who did not take part in the Champions Trophy - Giles, Panesar, opener Marcus Trescothick, Cook and paceman Matthew Hoggard - were likely to play against the Prime Minister's XI in Friday's one-day match in Canberra.
England then have two three-day games, against New South Wales in Sydney and South Australia in Adelaide.
The tourists have been given permission to play up to 14 players against NSW, but will play 11 against South Australia, and that match will be granted first-class status.
Fletcher said he, along with Flintoff, batting coach Matthew Maynard and bowling coach Kevin Shine, had discussed the likely Test line-up, and were close to finalising the team.
"We're pretty close. We had a good hour-and-a-half meeting yesterday throwing it around," he said.
"I was quite convinced what we'd require even before we came out here... we've got a good idea what we want."