The visitors lost three wickets for four runs inside the first two overs as quick Dushamantha Chameera dismissed Alex Hales and Jos Buttler in his first over after fellow quick Kasun Rajitha picked up Jason Roy.
Ben Stokes hit a defiant 31 as England moved to 63-4 in the 14th over. But Akila Dananjaya dismissed Stokes and Moeen Ali to have the Englishmen 129-8 in the 25th over. They were 132-9 in the 27th over when rain intervened and stopped play, resulting in the hosts winning by 219 runs (D/L method).
England thus took the series 3-1.
Earlier, openers Niroshan Dickwella and Sadeera Samarawickrama made a flying start, bringing up the 100-run stand in the 13th over. Dickwella went on to score a 50 off 49 deliveries as the hosts took grip of the final match.
Samarawickrama was out for 54 as Moeen Ali finally broke the opening stand for the hosts. Dickwella then departed for 95 as he became Ali’s second wicket. Kusal Mendis then got into the act, striking a 33-ball 56 to put on a 122-run stand for the third wicket.
Captain Dinesh Chandimal chipped in with 80 from 73 balls as the hosts amassed 366-6.
Tom and Sam Curran became the first brothers to play in the same England side in almost 20 years. They follow in the footsteps of Ben and Adam Hollioake, who were the last siblings to play together for England in February 1999.
With Eoin Morgan rested, Jos Buttler leads the side which also includes Liam Plunkett and Mark Wood.
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