In front of a sell-out crowd of 13,260, Yorkshire produced a curious display that promised much more than it ultimately delivered.
It was all going so well for the hosts when they were 102-1 at the halfway stage of their innings after winning the toss on a true batting pitch.
David Willey and Tom Kohler-Cadmore were in the throes of a second-wicket stand of 129, the joint third-highest for Yorkshire in T20, but the innings fell away to 181-9 as Lancashire fought back.
Willey top-scored with 80 from 43 balls with seven fours and five sixes, his second-highest T20 score for the county, and Kohler-Cadmore weighed in with 46 from 33 with six fours.
But those were the only meaningful contributions as a poor end to the innings was followed by a toothless bowling effort, Lancashire winning with 14 balls to spare to end a sequence of four games without a victory and leapfrog a Yorkshire side who dropped to fourth in the North Group.
Karl Brown scored 51 from 34 balls with five fours and two sixes, while Arron Lilley hit a T20 career-best 47 from 20 balls with four fours and four sixes.
In warm sunshine Yorkshire made a poor start when Adam Lyth chipped the second ball back into the hands of bowler Steven Croft.
It should have been 15-2 in the fourth over, but Alex Davies, fielding in front of a boisterous West Stand, dropped Kohler-Cadmore low down after the batsman pulled Jordan Clark when he had nine to his name. It changed the early mood, Willey following up with successive boundaries off Clark as Lancashire’s bowling and fielding became increasingly sloppy.
The score had rocketed to 55-1 by the end of the six-over powerplay, Willey lofting James Faulkner for six over mid-wicket before striking successive leg-side maximums off left-arm spinner Zahir Khan.
Willey later pulled Zahir for another six to go to fifty from 31 balls, and Yorkshire looked in complete command when Clark – who took a hat-trick against them in last month’s County Championship Roses match – conceded five wides in a 10th over that comprised 11 balls.
Kohler-Cadmore was dropped for a second time on 31, Lilley the culprit off Matt Parkinson as he tore in from long-on, Willey rubbing salt into the wounds by launching the leg-spinner’s next delivery for a huge straight six. But the England man finally went for one big hit too many, skying Danny Lamb to cover where Mark Watt clung on to leave Yorkshire 130-2 at the end of the 12th.
Kane Williamson was bowled by Zahir in the next over, and Yorkshire slipped to 142-4 in the 15th when Kohler-Cadmore got under an attempted straight hit off Parkinson and skied high into the off-side. Jonny Tattersall chipped in with 22 off 15 before sweeping Zahir to deep square-leg, where Davies this time held on.
Gary Ballance picked out Croft at long-on off Parkinson before James Faulkner took three wickets from the last four balls, bowling Jordan Thompson and having Azeem Rafiq and Steve Patterson caught at cover.
Lancashire began rapidly, Davies and Karl Brown adding 57 for the first wicket inside six overs before Davies was bowled by Patterson after striking 34 from 21 including three sixes.
The visitors kept finding the boundary as Rafiq was hit for consecutive leg-side sixes by Lilley, who was eventually dismissed courtesy of a brilliant diving catch at deep mid-wicket by Willey off Thompson.
By that stage, the score was 114-2 in the 11th, and although Dane Vilas was caught at short third-man and Brown run-out, the result was never in question.