Lancashire 218 for 5 (Croft 94) beat Worcestershire 193 for 7 (Whiteley 89*, Maxwell 3-23) by 25 runs
Lancashire Lightning secured a top two spot - and a home quarter-final - in the Vitality Blast North Group with a 25-run victory over holders Worcestershire Rapids at Blackfinch New Road.
Steven Croft hit a career equalling 94 as the Lightning totalled a formidable 218 for 5 after being put into bat. Saqib Mahmood then pressed home Lancashire's advantage by removed Rapids openers Hamish Rutherford - the overseas replacement for Martin Guptill - and Riki Wessels in his first two overs.
The game was effectively ended when Rapids captain Moeen Ali became the first of two wickets to fall in spinner Glenn Maxwell's first over and the Australian ended with the excellent figures of 3 for 23 from four overs.
Some typical hitting by Ross Whiteley - including his 100th T20 six for Worcestershire - kept the capacity 4500 crowd entertained. The Rapids are still very much in contention to reach the knockout stages but now face a crucial game against Notts Outlaws at Blackfinch New Road on Wednesday.
The Rapids opted to field first and struck an immediate blow with Alex Davies top-edging the first delivery of the game from Dillon Pennington to keeper Ben Cox.
Wayne Parnell shared the new ball and Steven Croft helped his first delivery over the fine leg boundary for six. Liam Livingstone collected four boundaries in Parnell's second over and the Lightning half-century came up in 4.1 overs.
Croft raced to his half century off just 24 balls with four sixes and four fours. Livingstone helped him add 83 in eight overs before he lofted Ed Barnard straight to Whiteley at deep midwicket.
Maxwell flicked Pat Brown over the fine leg boundary for six but tried to repeat the shot from the next ball and was pouched by Pat Brown. Captain Dane Vilas made a quickfire 23 before he cut hard at Barnard and picked out Rutherford at third man.
Daryl Mitchell bowled a tight mid innings spell and his four overs cost only 26 runs. But Croft continued to blaze away and hoisted Brown for two sixes in an over costing 22 runs. He moved onto 94 before attempting a slog-sweep in the final over from Moeen Ali and was stumped.
Croft faced 55 balls and struck six sixes and six fours and his fifth wicket partnership with James Faulkner was worth 60 in five overs.
When the Rapids launched their reply they were immediately on the back foot as Rutherford lobbed a Mahmood delivery to mid-on and Wessels perished at deep midwicket. Tom Fell was taken at long on - a fine low catch by Croft - off legspinner Matt Parkinson and then Maxwell's introduction to the attack paid double dividends.
Moeen was bowled by his first delivery and then Parnell perished at long-on. The Rapids lost half their side for 59 and required 151 from the final 10 overs.
Whiteley reached a 20 ball half-century, which included 26 from an over by Richard Gleeson. It included two sixes and seven fours.
An entertaining stand of 86 in eight overs with Cox ended when the keeper provided Maxwell with a third scalp with Davies this time holding onto the chance at deep midwicket. Whiteley ended unbeaten on 89 from 40 balls as the Rapids closed on 193 for 7.