Strauss was not impressed with some of England's fielding
Andrew Strauss criticised England's fielding after Australia secured a four-wicket win at Trent Bridge to take a 5-0 lead in the one-day series.
England made 299, by far their biggest total in the series, but Ricky Ponting's century steered Australia to victory with 10 balls remaining.
England captain Strauss said: "With the bat we were far more positive and we played in a much better manner.
"But we didn't help ourselves with some of our fielding, it was disappointing."
He went on: "That's something there should be no excuse for. I do know we work very hard on our fielding and we fell short of the standards we set ourselves today."
Strauss was, however, pleased to see Middlesex team-mate Eoin Morgan make his first significant score for England since shifting allegiance from Ireland.
Strauss said of Morgan, who made 58 from 41 balls and struck three sixes: "I've seen him play like that a lot for Middlesex and it's great to see him transfer those talents into the international arena.
"Without the likes of Andrew Flintoff and Kevin Pietersen it's up to others to stake a permanent place and Eoin did his chances no harm at all."
Australia skipper Ponting was man of the match after hitting three huge sixes in a sublime 126 off 109 balls.
Ponting said: "It was a tough chase but the ball got a bit dewy later on which probably helped us chase down those runs.
"Myself and Michael Clarke [who hit 52] put us in a good position. I didn't know when to take the powerplay, but even when I got out it wasn't much more than a run a ball required so I was confident the guys down the order could get us there.
"It was nice to get time in the middle. We were a little bit off with the ball and a little bit off in the field but we want to make sure we hit the Champions Trophy with all systems going."
The sixth match of the series takes place at Trent Bridge on Thursday, with the final match coming at the Riverside on Sunday.
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