England must pull off their near record one-day international run chase to seal the Royal London series after centurion Kumar Sangakkara powered Sri Lanka to 300 for nine at Lord's.
Sangakkara (112) dominated a second-wicket stand of 172 with Tillakaratne Dilshan (71) on the way to recording a hundred at the home of cricket for the first time in his illustrious career.
After Alastair Cook had put the tourists in on a sunny morning, the onus was therefore on him and his fellow batsmen to register a first series success in his and returning coach Peter Moores' new era.
They might have been chasing many more had England not fought back well on a good pitch, despite Sangakkara's 19th ODI hundred from only 95 balls.
The veteran number three began patiently - it took him 13 balls to get off the mark - but went on to bat on a different level to his team-mates, including Dilshan, with some expert footwork and placement for his 14 fours.
Harry Gurney, with a career-best four for 55, and Chris Jordan then each took two wickets in their final overs as the late trade-off marginally favoured England.
Kusal Perera, replacing Dinesh Chandimal on the sheet but in Lahiru Thirimanne's opening position, began the Sri Lanka innings with successive boundaries off James Anderson.
He added a pulled six off Gurney, but when trying to thrash the left-armer to leg again, he could only toe-end a looping catch to slip where Jordan dived to his left to hold on.
A battle of will and skill ensued between Dilshan and Anderson.
One memorable over, the ninth, included successive variations of the 'Dilscoop' for four, a play-and-miss attempting a third boundary in the same fashion and then a fortunate glove for two over the wicketkeeper's head as Anderson brought one down the slope.
Despite his initial watchfulness, however, it was Sangakkara who was soon outscoring his partner.
He gathered momentum with three fours from consecutive deliveries off Joe Root - straight past the bowler, over mid on and then through cover after Cook had brought the sweeper in as he juggled his field to protect other areas.
Sangakkara reached his half-century first as he and Dilshan maintained a tempo in excess of five an over.
The pair milked England's fifth bowler - Root and Ravi Bopara combined - until Dilshan lost leg stump to Anderson, moving across his crease again to try to manufacture a fine sweep.
That was one of two wickets for 24 in powerplay - this was not Mahela Jayawardene's day - but Sangakkara stayed long enough to complete his century before he was stumped on the charge from the first delivery of the impressively economical James Tredwell's final over.
It then fell principally to captain Angelo Mathews to ensure Sri Lanka did not squander a perfect platform, despite the late clatter of wickets.