Defeat by 20 runs to Sri Lanka at Headingley left their World Cup dream in danger of collapse.
England’s second defeat in six matches, to go with four wins, left them third in the table and with three group games left against the teams who have been tipped to join them in the semi-finals.
They face Australia at Lord’s on Tuesday, India at Edgbaston tomorrow week and New Zealand at Chester-le-Street on July 3, with the favourites probably needing at least one more win to reach the last four.
After Sri Lanka scored 232-9 from their 50 overs, Angelo Mathews top-scoring with an unbeaten 85 and Mark Wood and Jofra Archer each taking three wickets, England were dismissed for 212 with three overs left.
Ben Stokes struck an undefeated 82 and Joe Root 57, but Lasith Malinga took 4-43 and Dhananjaya de Silva 3-32 as Sri Lanka completed a famous win.
Asked whether defeat was a blow to his side’s hopes of reaching the semis, captain Morgan claimed: “No, not at all.
“It’s a long, long tournament and there are huge opportunities in every game, and we have three more to go.”
On a pitch on which run-scoring was never easy, with both teams struggling to find their rhythm, England seemed on course until Moeen Ali’s dismissal in the 39th over triggered a collapse from 170-5.
Moeen, playing his 100th one-day international, holed out on the straight boundary off de Silva, one delivery after smashing him over the leg-side rope.
Stokes made a valiant attempt to see his side home, striking four sixes and seven fours in an innings that comprised 89 balls, but he was left stranded when Durham team-mate Wood was last out.
“In the chase, we didn’t do the basics of getting substantial partnerships going,” said Morgan.
“We had a couple of good individual performances, but Sri Lanka thoroughly deserved to win here.
“We didn’t do enough to win the game, and even if we had nicked it then it would have been us robbing the game with an outstanding individual performance.
“I don’t think it affects confidence; when we get beaten we tend to come back strong and resort to aggressive, smart, positive cricket, and let’s hope that’s the case against Australia.”
Asked what his message is to his team ahead of that match, Morgan added: “The message is quite simple – we need to do the basics better.
“The fact is that we are going to lose games in the group stages and we didn’t deserve to win this game.
“The belief is there, and there’s no reason why it shouldn’t be.
“We just didn’t overcome the challenges that presented themselves on this occasion.”
Dimuth Karunaratne, the Sri Lanka captain, praised his side after a result that left them fifth in the table.
“It was a close one; we were under pressure, but it was teamwork in the end,” he said.
“We thought that the wicket looked like a 300 pitch, but it was slower than we thought.
“We knew we couldn’t get 300, so wanted 250-275 until we lost some wickets and Angelo Mathews batted really well.
“With a score on the board, the bowlers knew what to do.”
Rather than Moeen’s wicket, Karunaratne thought that Root’s dismissal was the pivotal moment, the Yorkshireman fourth out at 127 in the 31st over when he was given out on review, caught down the leg-side off Malinga.
“The Root wicket was the turning point,” he said.
“We were not confident but thought we would go for the review, and thankfully it worked.”