On a good pitch, the challenge for England's bowlers will be to prevent Australia reaching their target in less than 40 overs, which would gain them a bonus point in the CB Series table.
England have offered few clues about which man they intend to pick. And it remains possible that both could play.
McGrath's arrival in the attack, when his first ball was pulled by Loye through midwicket and his second slog-swept for another boundary, was soon put behind him.
"Mal is a definite option for us, he opens the batting for Lancashire where he has been successful," said stand-in captain Andrew Flintoff.
Loye, aged 34, was flown in from New Zealand, where he was playing state cricket, to play in his 264th one-day match when Michael Vaughan injured his hamstring
If I have to go out and play I'll treat it like another game at Chelmsford Ravi Bopara
His front-foot shot off Lee in the fifth over would not have looked out of place in any of the previous 263, played for Northants and, for the last three years, Lancashire.
Loye, whose signature shot is a front-foot slog sweep off fast bowlers, said: "If I play tomorrow or in the next few days it would be the ultimate."
Lee, returning after a bout of bronchitis, topped the 90mph mark straight away but took a while to find his feet.
Bopara hit a century for Essex against the Australians in 2005 and also bowls.
At the other end, though, left-armer Bracken was a model of consistency, his opening six-over spell costing just 14, including a single boundary.
He said: "I have been taught always to expect the unexpected.
The wicket of Loye was a just reward, as he shaped the ball away to gain an edge to a wide first slip.
"Since coming here [with the Academy] I've learned a lot in terms of batting.
Loye slog-swept Lee for six and took two boundaries off McGrath
"I've learned a lot about bowling on these pitches too. Every time I come out here I learn a bit more.
Andrew Strauss had a less assured start than his new team-mate, although an edge over slip off Lee for six indicated his luck might be turning after a difficult tour.
"If I have to go out and play I'll treat it like another game at Chelmsford."
An athletic diving, one-handed catch by cover fielder Brad Hodge proved to the contrary, punishing an uncontrolled pull shot with his score 18.
It was down hill from there for the tourists, denied singles by the accuracy of McGrath, Bracken and then Mitchell Johnson on his home ground.
If England choose to drop Middlesex's Ed Joyce, or even dispense with Jamie Dalrymple, then both Bopara and Loye would secure a starting berth.
Ed Joyce endured another failure, getting an inside edge behind with a loose push, and Paul Collingwood edged his first ball behind in McGrath's next over to force Paul Nixon to avoid the hat-trick.
Australia will be captained by wicket-keeper batsman Adam Gilchrist, with Ricky Ponting resting.
In-between, England's disastrous season was summed up by the run out of Ian Bell, initially ignoring non-striker Collingwood's call for a single to Cameron White at backward point.
Premier pace pair Glenn McGrath and Brett Lee return having been out with a sore groin and a bout of bronchitis respectively.
Even though White could only roll the ball along the ground, it dislodged the bails with Bell still making up his mind a yard outside his crease.
Brad Hodge comes in to replace resting captain Ricky Ponting
Back as skipper, Andrew Flintoff looked to steady the ship in 12 overs at the crease alongside Nixon and Dalrymple.
Lee will start for the first time in the series, while McGrath missed the win against New Zealand after taking 2-40 in the opener against England.
He was just beginning to open up - and was only denied a six by a dubious television replay - when another outstanding catch from Hodge, at deep square leg, stopped him abruptly.
Gilchrist said McGrath, despite his terrific record for Australia, could not feel entirely secure about his place in the side.
Nixon edged Lee to slip with a tentative prod and Dalrymple's performance made their switch in the batting order seem ill-advised.
He said: "If the hard call had to be made throughout the tournament on one of the more experienced players, the selectors and team management would make it.
As tail-end wickets continued to tumble, though, Dalrymple's hoick to long on made little difference to a miserable picture.
"I don't want to just single out Glenn. Whether it's a batsman or a keeper-batsman, that call will be made, there's no doubt about it.
"It's not a farewell tour for Glenn. Everyone's aware of that and no-one more so than Glenn."
Realistically, Australia are not expected to be threatened much by either England or New Zealand in the remainder of the series.
Victoria batsman Brad Hodge takes Ponting's place in the batting order, with Lee replacing Stuart Clark in the only other change to the team that beat England in Melbourne.
It means England's flaky batting unit faces the strongest bowling side Australia can put out in one-day cricket.
Australia: AC Gilchrist (captain, wkt), ML Hayden, BJ Hodge, MJ Clarke, A Symonds, MEK Hussey, CL White, NW Bracken, MG Johnson, GD McGrath, B Lee.
England (from): A Flintoff (captain), AJ Strauss, IR Bell, MB Loye, PD Collingwood, EC Joyce, RS Bopara, JWM Dalrymple, PA Nixon (wkt), JM Anderson, J Lewis, MS Panesar, CT Tremlett, SI Mahmood, LE Plunkett, CMW Read (wkt).
Umpires: DJ Harper & IL Howell (South Africa). Match referee: RS Madugalle (Sri Lanka)
