Andrew Strauss lamented England's poor fielding display as they slumped to a four-wicket loss to Australia in the fifth match of the NatWest Series.
The hosts piled up 299 after batting first at Trent Bridge, comfortably their best effort of a miserable series.
But Australia, led by skipper Ricky Ponting's century, chased down their target with 10 balls to spare to open a 5-0 lead heading into the final two games.
"The fielding was poor, to be honest," England captain Strauss admitted.
"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 also conceded there was little he could do in the face of Ponting's onslaught as the Tasmanian cantered to 126 off just 109 balls and shared a 133-run partnership with his deputy Michael Clarke (52), which came from just 134 deliveries.
"The bowling could have been better, but Ponting and Clarke in particular played exceptionally well," Strauss added.
"They put Australia in a position to win, and then at the back end we weren't able to apply as much pressure as we would have liked - because our fielding let us down."
After his team's troubled series so far with the bat, Strauss was at least happy to reflect on a better display - in which Eoin Morgan's 41-ball 58 was the highlight.
"There were some bits of today that were encouraging," he added.
"I thought our batsmen went out and played with a bolder approach, and that paid dividends.
"Eoin Morgan in particular embodies that. I thought he played exceptionally well. It's the way he's played for Middlesex in the past, so that was encouraging.
"I thought we were closer to our potential today as a batting unit."
With the possibility of whitewashing England in the seven-match series growing increasingly likely, Australia have the chance to earn more revenge for their Ashes defeat.
Ponting, however, played down the significance of that scenario with two games to go - the series resumes in Nottingham on Thursday before concluding at the Riverside on Sunday - saying instead his team are trying to build confidence for the start of the Champions Trophy, which starts in South Africa on September 22.
"I stressed to the boys yesterday the importance of these remaining games heading into the Champions Trophy around the corner," Ponting said.
"The application today shows that the boys are up for finishing this series well.
"That's a good sign for us. I hope we'll play well on Thursday and again on Sunday and head to South Africa with a bit of confidence.
"I felt like I played well. It was a really good run chase and it just goes to show we are heading in the right direction with our one-day cricket heading into the Champions Trophy."