Joe Root became the youngest England batsman to score a World Cup century as England set Sri Lanka 310 to win their Pool A clash in Wellington.
England raced to 62 without loss before Moeen Ali's poorly-timed shot saw him pick out Suranga Lakmal at mid-off.
Gary Balance's dismal tournament continued as he was dismissed for six and when Ian Bell fell for 49, England's innings looked to be in danger of faltering at 101-3.
Root put on 60 for the fourth wicket with Eoin Morgan (27) before the captain's fierce cut shot went straight to Tillakaratne Dilshan at gully.
However, England continued their recovery and Root reached his century off 101 balls as he and James Taylor (25) attacked in the final 10 overs, with Lakmal taking plenty of punishment.
Lasinth Malinga (1-44) returned to remove Taylor and Rangana Herath trapped Root lbw for 120 as Sri Lanka looked to halt England's progress.
Herath was then forced off with a suspected broken finger sustained when they trying to take a return catch off a fierce Jos Buttler drive in the penultimate over.
England managed to surpass 300 thanks to Buttler's 39 from 19 balls as Sri Lanka's struggled to restrict their opponents.
