Skipper Glen Chapple led the charge as Lancashire booked their place in the semi-finals of the CB40 with a 18-run victory at Gloucestershire.
Chapple took 5-26 as the hosts were dismissed for 164 at Bristol after Lancashire had posted just 182-9 in their 40 overs.
Ashwell Prince (25) and Steven Croft (31) had given Lancashire a positive start but they collapsed from 70-2 to 98-5.
Left-arm spinner Ed Young again impressed for the hosts, taking 3-25 and Lancashire were grateful to Oliver Newby (36 not out) for posting a total they had a chance of defending.
But Chapple's devastating early burst left Gloucestershire reeling on 16-4, with Kiwi import Rob Nicol and in-form Dan Housgo back in the hutch.
The Gidman brothers Alex (36) and Will (32) led a rally and another Kiwi, James Fuller whacked 43 to keep the hosts in the game.
But veteran Chapple returned to snare the tail and ensure his side a passage through to the last four.