England won the toss and elected to bat but Cook’s men slipped to 62-3 before Gary Ballance and Eoin Morgan both scored half centuries to steady the ship.
270 would have been defendable if we’d bowled right
Michael Clarke’s side eventually limited England to a “defendable” score of 269 before opener Aaron Finch hit 121 runs off 128 balls to put the hosts in charge.
Australia didn’t lose a wicket until David Warner fell to leave the home side on 163-1, and Clarke’s men sealed a comfortable win with six wickets to spare.
“We were about 20 runs short but we didn’t bowl in the areas we wanted to,” Cook told BBC Sport.
“270 would have been defendable if we’d bowled right. You’ve got to get yourself in early on – Aaron Finch and David Warner didn’t hit out straight away, they built a partnership.
“We kept building partnerships for 20 or 30 but then getting out. I was very impressed with Chris Jordan and Gary Ballance today.
“But it’s one-day cricket, we’ve got a lot of talent and firepower in that batting line-up.”
Australia captain Clarke praised his attack, as well as hailing the win as perfect preparation ahead of this year’s 50-over World Cup.
“We were a little bit sloppy in the field, our bowlers did well and our batters were outstanding,” Clarke said.
“Our momentum has come from the series we played in the UK. The ODI team is different to the Test team, but we are still full of “We aren’t thinking about the World Cup, but this
is still fantastic preparation.”
England can exact revenge on Australia in the next ODI in Brisbane on Friday.
MORE: The latest football news
MORE: The latest tennis news