England 189 for 5 (Root 79*, Chameera 3-50) beat Sri Lanka 185 (Perera 73, Hasaranga 54, Woakes 4-18) by five wickets
It's not as if this profoundly depleted Sri Lanka side did not have their moments.
During the 99-run fourth-wicket stand between Kusal Perera and Wanindu Hasaranga, a creditable total seemed possible. When the seamers, led by Dushmantha Chameera, claimed four England wickets for 26 runs, leaving the opposition 80 for 4 (it would have been 80 for 5 if Perera had held on to dismiss Moeen Ali first ball, off Chameera), there was the slim possibility of making the run-chase difficult for England.
But because the remainder of the game went roughly as expected, England's victory was straightforward, ultimately. Sri Lanka lost 3 for 45 at the top of their innings, then their last seven for 40, making an eventual 185 that was miles form being sufficient.
England's new-ball bowlers had set the match up - Chris Woakes particularly disciplined and skilful as he claimed 4 for 18 from his 10 overs. Then Jonny Bairstow blasted a 21-ball 43, and Joe Root nurdled his way to the game's top score of 79 not out, Moeen keeping him company through most of it. England had bowled Sri Lanka out inside 43 overs. They surpassed their score inside 35 overs, with five wickets to spare.
A comfortable England victory had anyway been expected following the T20Is, which they had easily won, but the gulf between the sides had widened further when it became clear that no fewer than six of Sri Lanka's original touring squad were unavailable for this game. Bio-bubble-popping trio Danushka Gunathilaka, Niroshan Dickwella and Kusal Mendis were already in Sri Lanka before this match began, having been flown back in economy class for their sins. Avishka Fernando and Dhananjaya de Silva, meanwhile, were out through injury, and Oshada Fernando was unavailable due to illness.
This left the visitors with little choice but to field a slew of inexperienced players. Three - allrounders Charith Asalanka and Dhananjaya Lakshan, plus left-arm spinner Praveen Jayawickrama - were on ODI debut. Three others - Binura Fernando, Ramesh Mendis and Chamika Karunaratne - had played only one ODI. On top of which Pathum Nissanka was playing his seventh match. In fact, across their XI, Sri Lanka only had 195 caps - 105 of them belonging to captain Perera. Eoin Morgan was playing his 244th game.
Woakes and David Willey ensured that England began the match as expected, extracting seam and swing in the first Powerplay, though Woakes in particular would probably have troubled even much better opposition. He rarely strayed from the channel, finding movement both in the air and off the surface, and nicked off Nissanka in the fifth over. Four overs later he bowled the delivery of the innings when he angled a ball in from over the wicket, then moved it away off the seam to take the edge of Dasun Shanaka. At the other end, Willey had had debutant Asalanka caught at slip for a duck.
After Perera and Hasaranga had each struck fifties, it was these two bowlers who came back into the attack to rip through the middle order. Woakes bounced Hasaranga out for 54, before nicking Lakshan off soon afterwards. Perera had been Sri Lanka's most settled and confident player, but perhaps sensing a collapse from his team-mates, holed out to deep square leg off the bowling of Willey, for 73 off 81. That Perera could produce these kinds of innings was known, but Hasaranga's half-century was encouraging - he had come in at No. 5 and had to battle through some excellent seam bowling before finding his feet against the spinners.
In reply, Bairstow was brutal in the early overs, bashing six fours and a six in his 21-ball stay to propel England at greater than 10 runs an over in the early overs of their innings. But when he chopped Binura Fernando on to his stumps, England had lost both openers in quick succession - Liam Livingstone having spooned Karunaratne to mid-on the previous over.
Then, Chameera - the best of Sri Lanka's bowlers - had Eoin Morgan caught behind, and Sam Billings flashed one aerially to backward point. His next ball should have accounted for Moeen too, but Perera was standing too far to the leg-side, and was late moving towards his left. He spilled that chance, and England rebuilt.
Root's innings was measured. There was little pressure from the required rate, so he chose to collect safe singles and twos into the outfield, relying heavily on a dab to third man against the quicks. In fact, in the whole of Root and Moeen's 91-run stand, only three boundaries were struck. Although Moeen did seem bogged down at times, ultimately striking at less than 50, Root was untroubled by the lack of boundaries. He guided England home in the company of Sam Curran.

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @afidelf