Yorkshire 325 for 7 (Lyth 136) beat Lancashire 84 (Guptill 45, Willey 3-44, Carver 3-5 ) by 242 runs on D/L method
Adam Lyth became the first Yorkshire batsman to score two List A hundreds in successive days as Lancashire were blown away chasing 327 at Emirates Old Trafford in the Royal London Cup.
Lyth posted 125 off 78 balls against Northants at Scarborough on Tuesday before usurping his career best with 136 off 92 at Old Trafford in good batting conditions.
His 12 fours and seven sixes were the feature of Yorkshire's 325 for 7 from 47 overs, with Duckworth Lewis later upping the Lancashire target by one run following earlier rain.
The Lightning, who had been 53 for 1, then slumped to 84 inside 18 overs to lose by 242 runs. Martin Guptill was the only batsman to reach double figures with 45.
It was Yorkshire's biggest ever winning margin and Lancashire's biggest ever losing margin in List A cricket.
David Willey, just back from bowling after injury, took three wickets and left-arm spinner Karl Carver finished with 3 for 5 from three overs.
Ashley Giles, Lancashire's coach, said: "It was poor cricket from start to finish - with bat, ball, in the field and from a coaching perspective. If you lose like that, we all have to be accountable for it. There are no excuses, we played bad cricket.
"They got too many runs. Lyth played well, but we didn't bowl enough balls in the right place. Not to get anywhere near and, in the manner we got out, you have to show more application and play better shots. From start to finish, it was not good enough."
Lyth shared a partnership of 111 inside 16 overs for the second wicket with Kane Williamson, whose 40 was Yorkshire's next best score.
Left-handed Lyth reached his century off 60 balls against Northants at 4.22pm and here off 64 balls at 4.10pm. It meant he achieved the notable feat of recording two hundreds inside 24 hours.
Lancashire's bowlers were under the cosh for the vast majority of the innings, while their fielding could have been better.
Lyth was dropped on 83, an incredibly tough chance for Guptill at backward point, and again on 121 when Alviro Petersen parried the ball over the ropes for six at deep cover. He should have caught it.
Liam Livingstone's leg-spin accounted for 3 for 51 from eight overs, including the centurion caught at long-off.
Guptill helped Lancashire get off to an encouraging start with three sixes in 25 balls, but he was the first of Willey's wickets when he was bowled, leaving the score at 53 for 2 in the seventh.
Then, he saw five more wickets fall for four runs in 16 balls as the score slipped from 64 for 2 to 68 for 7 in the 13th.
Spinners Adil Rashid and Carver, with his first ball, struck in that period, as did Willey twice in two balls to get Jos Buttler caught behind for a duck and Steven Croft caught at point for a golden.
In all, Lancashire's last nine wickets fell for 31 runs. Willey's 3 for 44 from six was also supplemented by two each for Tim Bresnan and Rashid in a remarkable second innings of the match.