Yorkshire 180 for 8 (Willey 79, Lees 36, Ingram 4-32) beat Glamorgan 90 (Rashid 4-26) by
Yorkshire completed a quarter-final clean sweep for the North Group to join Nottinghamshire, Northamptonshire and Durham on NatWest T20 Blast finals day at Edgbaston a week on Saturday.
On a good pitch, they seemed to have left themselves slightly vulnerable when their last eight overs added only 46 to a 12-over score of 134 for 3 but Glamorgan lost five wickets for 34 in the Powerplay, after which Yorkshire's place in the semi-finals was all but guaranteed.
Jacques Rudolph, against his former teammates, offered a brief flurry of shots to keep the Cardiff crowd from going home embarrassingly early but as it was they were dismissed for 90 in just 13 overs, their lowest total of the season.
Adil Rashid arrived from The Oval to take four wickets for 26 but the performance of the night belonged to David Willey, whose 79 off 38 deliveries contained six sixes and ultimately underlined the disparity in terms of depth of quality that sets these sides so far apart, the one seeking to win a third County Championship in a row, the other at the bottom of Division Two.
Yorkshire have some momentum behind them now across all formats, their Championship campaign gathering pace and their hot streak in this competition continuing. Having offered little evidence that their problems mastering the shortest format were anywhere near being solved in the first half of the Blast season, when they won only one of their first seven matches, they now have seven victories in the last eight.
Willey is developing the useful habit of producing his best when it counts for most. A year ago he made 100 off 41 balls to power Northamptonshire into the semi-finals at the expense of Sussex on a thrilling night at Hove, having won the competition almost on his own three years earlier with 60 off 27 balls and 4 for 9 against Surrey in the final at Edgbaston.
He was into his stride immediately, driving Graham Wagg down the ground four consecutive fours before going after Michael Hogan with a hook for six, then two more strong hits for four.
Shaun Tait's opening over removed Adam Lyth with a slower ball struck straight to mid-off before Tim van der Gugten's second over conceded only two singles as Glamorgan responded but then an awful over from Tait, with a no-ball for over-stepping and another for a ridiculously high bouncer, was punished ruthlessly by Alex Lees, who lifted the free hit over the long on boundary as 22 were added.
It had been Glamorgan's most expensive powerplay of the season and it was a while before things got much better. Willey pulled a half-tracker from Craig Meschede for his second six before hitting sending two in a row into the crowd off Hogan to be 58 off 29 balls.
Lees, who had come close to matching his partner's aggression, miscued Wagg to long-off but Willey's assault continued with two more maximums before Colin Ingram, himself on the end of sixth one, produced a loopy googly that finally ended the butchery. Nonetheless, 134 for 3 off 12 was a handsome position.
From that platform, 180 for 8 felt like a disappointment, although still the highest score on this ground this season and perhaps 25 over par. Ingram, bravely giving the ball air and mixing googlies and leg spinners, finished with 4 for 32, his best figures in T20, and Tim van der Gugten kept his nerve too as Yorkshire lost six for 35 in six overs and four balls.
Tait recovered well from his mauling by Lees and at the end of the innings the quieter dug-out was the one occupied by Yorkshire.
How quickly that changed. Tim Bresnan removed David Lloyd with the first delivery of the new innings as the ball deflected off an inside edge on to the base of the stumps, sparking the crash of wickets that left Glamorgan in a hole from which there was no escape.
Mark Wallace drove Bresnan straight to short extra cover, Aneurin Donald missed completely with an ugly heave across the line, Matthew Waite, the 20-year-old seamer making his first appearance of the season, enjoyed the sight of Ingram top-edging a short ball to long leg and Liam Plunkett beat Wagg for pace.
Now Rashid, so adept at finishing things off, now moved in for the kill and four of the five remaining wickets were his, Plunkett taking an athletic boundary catch to dismiss Meschede, Andrew Salter succumbing to the googly, van der Gugten and Hogan departing two balls apart in what transpired was the last over. The only one to escape the England spinner was Rudolph, who holed out off Azeem Rafiq.