Joe Root struck his maiden one-day international score of over 150 as England beat the West Indies by three wickets in Cardiff on Sunday to take an unassailable 2-0 lead in a three-match series.
England were faltering at 2-2, chasing 309 for victory, after both Jamie Smith and Ben Duckett were out for ducks at Sophia Gardens.
But star batter Root's 166 not out saw England finish on 312-7 as they won with seven balls to spare ahead of Tuesday's finale at The Oval, despite West Indies fast bowler Alzarri Joseph's fine return of 4-31 from his maximum 10 overs.
Root received good support from England captain Harry Brook (47) – a series winner in his first campaign as permanent white-ball skipper – in a stand of 85.
Will Jacks (49) then helped Root add 143 in 20 overs during a sixth-wicket partnership that took England to the brink of victory.
This match also saw Root become England's leading ODI run-scorer, his tally of 7 082 runs in 168 innings surpassing retired World Cup-winning captain Eoin Morgan's mark of 6 957 in 207.
"From being 2-2, it was nice to be there at the end and get us across the line, winning the series with one game to go," said player-of-the-match Root at the presentation ceremony.
'AMAZING'
Meanwhile an elated Brook said: "Root – he is only getting better with age is that boy! It is amazing to have him in the side."
The West Indies were much-improved with both bat and ball following their humiliating 238-run loss at Edgbaston on Thursday, where England made exactly 400.
But despite the in-form Keacy Carty's 103 they were ultimately made to pay for not compiling a truly huge total when well-placed on 205-2 at Sophia Gardens.
"With the position we were in around that 35-over mark, we should have put on 30 to 40 more runs at least," said West Indies captain Shai Hope.
The West Indies were dismissed with 14 balls left as veteran legspinner Adil Rashid took 4-63 and paceman Saqib Mahmood, with two wickets in two balls, 3-37.
But their 308 all out looked a challenging total as England openers Smith and Duckett failed to score a run between them.
Root survived a tight lbw appeal from allrounder Matthew Forde on seven thanks to umpire's call before, next ball, Brook was dropped by diving wicketkeeper Hope off fast bowler Jayden Seales.
But the Yorkshire duo's stand was broken when Brook mishooked a Joseph bouncer to Seales in the deep.
And 87-3 became 93-4 when Joseph had Jos Buttler playing on for a duck after a rising delivery deflected onto the stumps off the batsman's elbow.
England were still faltering at 133-5 when Barbados-born Jacob Bethell, who made 82 at Edgbaston, was lbw to offspinner Roston Chase for 17.
Root, however, hoisted Gudakesh Motie for six and next ball swept the left-arm spinner for four to go to his 18th ODI hundred.
He then surpassed his previous highest score at this level of 133 not out against Bangladesh at The Oval in 2017 when he drove paceman Justin Greaves for a classic straight six.
Jacks' fine supporting innings ended when he was lbw to Joseph but England, at 276-6 in the 44th over, now needed under a run-a-ball to win.
Root completed his first ODI score of 150 with a majestic cover-driven four off Forde before hitting the winning runs when driving Seales down the ground.
CARTY RIDES HIS LUCK
Earlier, Carty struck his third hundred in four innings after Brook sent West Indies into bat.
England were not as sharp in the field as they had been at Edgbaston, with Carty missed on one and 41 in two of four dropped catches in the innings.
Carty and Brandon King (59) shared a second-wicket stand of 141 following the loss of teenage opener Jewel Andrew for a duck before Hope made 78.
The 28-year-old Carty completed his century when he late cut Bethell for a 13th four in 102 balls faced. But he was out soon afterwards when stumped by Buttler off part-time spinner Jacks.
England: Jamie Smith, Ben Duckett, Joe Root, Harry Brook (capt), Jos Buttler (wkt), Jacob Bethell, Will Jacks, Brydon Carse, Adil Rashid, Matthew Potts, Saqib Mahmood
West Indies: Brandon King, Jewel Andrew, Keacy Carty, Shai Hope (capt/wkt), Shimron Hetmyer, Justin Greaves, Roston Chase, Matthew Forde, Alzarri Joseph, Gudakesh Motie, Jayden Seales
