Captain Alastair Cook said England's batting was the chief disappointment after a six-wicket loss to Sri Lanka left the hosts trailing 2-1 in the five-match one-day series.
"I think we were about 30 or 40 runs light," the opener said after his team had set Sri Lanka 247 to win in good batting conditions at Lord's.
"It's been a tough day. We kept losing wickets at the wrong time.
"There are lots of areas we can improve on but we didn't get going at the top."
The teams face each other again in a day-night match at Trent Bridge on Wednesday, and England may decide to change their side following two comprehensive defeats.
Cook, who took over the captaincy of the one-day international side on a permanent basis at the start of the series, at least answered those questioning his batting ability in 50-over cricket with a century.
However, former England players Alec Stewart and Mark Butcher have questioned the balance of the side with Jonathan Trott batting at number three and Ian Bell at six in the order.
Asked if there were too many conservative batsmen in the side, Cook replied: "Like who?
"Trotty's had a quiet couple of games, but he averages 50 and strikes at 80 at number three, which are pretty good stats.
"We'll all take collective responsibility in the batting line-up for not scoring enough runs. That's the reason why we didn't win this game.
"It's nice for a bit of confidence to score runs, but it's never nice to do it in a losing cause."
Former captain Stewart, speaking on the BBC's Test Match Special, said England needed to change the batting order and freshen up the bowling attack.
"There's certainly plenty of cause for concern for England not just with the batting, but the type of bowlers they have and the form of cricket they are they playing," he said.
"They need to play without fear and they they need to find a method to be successful in all conditions across the world."
His view was backed up by former England opener Butcher, who was also summarising on Test Match Special.
"England's problem in one-day cricket has always been that they don't have the impact players, the players that can win you matches with a burst of wickets or runs with the bat," he said.
Sunday's match at Lord's ended in bizarre fashion when Dinesh Chandimal and Angelo Mathews refused a succession of runs to ensure Chandimal, 21, could reach a century at Lord's.
Mathews finished unbeaten on one not out from 21 balls, having defended the 47th over of the innings for a maiden in a period of play which perplexed both captains.
"It was different. I've never seen that before," said Cook. "They're perfectly entitled to do it if they want. It's just slightly strange and you never know, the cricketing gods might look down in a bit of disgust. It was getting close, wasn't it?"
Sri Lanka captain Tillakaratne Dilshan looked visibly irritated on the balcony but said afterwards: "We won comfortably in the end. I was a little upset that it came down to the last overs, but they are youngsters, they are learning, and I'm really happy because we got a good win.
"We are very confident after the last two games and looking forward to winning the series."