PRO40 Division One, Liverpool
Somerset 157-7 (39.4 ovs) bt Lancashire 156 (39.1 ovs) by three wickets
Lancashire have been relegated from Pro40 Division One after suffering a three-wicket defeat against Somerset, whose win keeps them in the top flight.
Somerset seamer Mark Turner took 3-39 to reduce Lancashire to 75-7 before Glen Chapple's 33 not out helped the home side to 156 all out at Liverpool.
Tom Smith then took two wickets as Somerset slumped to 91-5.
But Carl Gazzard (30no) and Alfonso Thomas (11no) guided the visitors to a three-wicket win with two balls left.
The result means that, in the final Pro40 season before the competition is scrapped, Lancashire will play in Division Two for the first time since 2003.
Put in to bat by Somerset captain Justin Langer, Lancashire's innings fell apart through a mix of questionable shot selection and impressive work in the field by the opposition.
While 23-year-old Turner was the pick of the bowlers, Peter Trego, Thomas and Zander de Bruyn all picked up two wickets apiece and Charl Willoughby got one.
Lou Vincent, Steven Croft (20), Francois Du Plessis, Gareth Cross and Tom Smith (18) were all guilty of poor shots for Lancashire.
And although Gary Keedy was stumped by Gazzard off the bowling of de Bruyn, he at least showed the way with a compact 23 including two classical drives.
Not only was Somerset's bowling impressive, taking advantage of early movement through the air and off the pitch, their fielding was also slick.
Marcus Trescothick, Wes Durston and Arul Suppiah all grabbed sharp chances while wicketkeeper Gazzard claimed four dismissals.
Lancashire gave themselves some hope when Chapple bowled Trescothick and Oliver Newby had Langer caught behind by Cross to reduce the visitors to 34-2.
But wicketkeeper Cross then dropped Suppiah on two off the bowling of Chapple and Newby conceded 34 runs in his opening five overs.
Smith trapped de Bruyn lbw for 18 and removed James Hildreth courtesy of a fine catch at first slip by Paul Horton.
Left-arm spinner Keedy bowled Suppiah for 33 and Croft had Trego caught behind down the leg-side.
Keedy got his second when he trapped Wes Durston leg before wicket to leave Somerset needing 36 from the last six overs.
Gazzard and Thomas held their nerve to retain their side's Division One status.