England seemed to be cruising towards a comfortable victory on Sunday after restricting Australia A to a modest total of 205 for nine then racing to 111 for three in reply.
The tourists lost their last seven wickets for just 71 runs to succumb to 182 all out from 47 overs and crash to a 23-run defeat.
Captain Nasser Hussain and all-rounder Ronnie Irani both made 33 but Craig White (1) and Ian Blackwell (6) were both run out while a number of other players threw their wickets away with rash shots.
England's batting collapse ruined what had been a markedly improved display by their bowlers and fielders who succeeded in frustrating the Australians with a tight line and length.
Man of the match Irani captured three vital wickets during a tidy 10-over spell that cost just 30 runs while Nick Knight underlined the improvement in England's fielding with two brilliant catches.
He took a sharp catch at point to get rid of Greg Blewett for 23 then held an even better one-handed catch at slip to remove Andrew Symonds for three.
PATIENT LANGER
Australia A captain Justin Langer hit four fours and a six in compiling a patient 62 off 103 balls to set his team up for a bigger total before the home side's middle-order collapsed.
The Australians slumped to 188 for nine until Mike Hussey carefully propped up the tail with an unbeaten 44 from 47 deliveries.
England made a terrible start to their reply when White was run out in the second over but Irani and Knight added 56 at better than a run a ball to steady the innings and put the tourists back on track.
But Irani, who hit seven boundaries in his 22-ball innings, departed when he was trapped leg before wicket by Ashley Noffke's first delivery.
Hussain made 33 off 72 balls when he was trapped in front by chinaman bowler Brad Hogg, who finished with 3-32, with the total on 110-4 as the Australians suddenly found themselves back in the game.
With just 96 needed, England still had a chance to win but Hussain's dismissal triggered another familiar collapse and the last four wickets tumbled for just 32 runs, condemning the tourists to another defeat.
England lost their first one-day practice match against New South Wales by eight wickets on Friday after heavy defeats in each of the first three Ashes tests.
They play the Prime Minister's XI in Canberra on Tuesday before facing the full-strength Australian side in Friday's opening match of the triangular international series that includes Sri Lanka.
| VB Tri nation Series in Australia 2002-03 | |||
| 13 December | Australia v England | Sydney (d/n) | |
| 15 December | Australia v England | Melbourne (d/n) | |
| 17 December | England v Sri Lanka | Brisbane (d/n) | |
| 20 December | England v Sri Lanka | Perth (d/n) | |
| 22 December | Australia v Sri Lanka | Perth (d/n) | |
| 9 January | Australia v Sri Lanka | Sydney (d/n) | |
| 11 January | Australia v England | Hobart | |
| 13 January | England v Sri Lanka | Sydney (d/n) | |
| 15 January | Australia v Sri Lanka | Brisbane (d/n) | |
| 17 January | England v Sri Lanka | Adelaide (d/n) | |
| 19 January | Australia v England | Adelaide (d/n) | |
| 21 January | Australia v Sri Lanka | Melbourne (d/n) | |
| 23 January | 1st Final | Sydney (d/n) | |
| 25 January | 2nd Final | Melbourne (d/n) | |
| 27 January | 3rd Final (if needed) | Adelaide (d/n) | |
