Shaun Pollock, Warwickshire's South African all-rounder, conceded 14 runs to Graham Lloyd and Peter Martin in a tantalising penultimate over, when 17 had been needed.
Their effort frustrated Dermot Reeve, Warwickshire's captain, ace tactician and taker of three catches and three wickets. It was Warwickshire's first defeat in any competition this season, with Lloyd's gold-award- winning innings of 63 not out from 40 balls including six lavish fours.
Lancashire are the Cup holders but Warwickshire lifted the NatWest Trophy last September and the shrewd money is already on their meeting somewhere further along the way in this restyled 50-over competition. Reeve's team have bubbling self-confidence but Lancashire also have a brashness about them, typified by Lloyd's ebullience.
Even so, the subtlety of Reeve's field placing exploited some loose Lancashire strokes, notably when Michael Watkinson, his opposing captain, had promoted himself in the order to set the score moving he pulled a catch to Reeve and Ian Austin, who was also moved up the batting order, played another wild stroke and was bowled. As for Warwickshire, they used a more conventional batting approach and all contributed something, notably Nick Knight and Neil Smith, who accelerated the total to 112 for 2 in 15 overs.
Smith's half-century took only 43 balls and Pollock later pillaged 59 not out from 48 deliveries. Gary Yates returned a creditable 3 for 65 but others proved expensive. Michael Atherton fielded admirably, holding a sharp catch to dismiss Dominic Ostler but the England captain did not prosper long in Lancashire's reply.
Atherton failed to offer an authentic stroke to Ashley Giles and was leg-before, but Lancashire acquired 100 for 2 from 15 overs before sustaining their tempo in the rush for victory.
Dougie Brown, who had batted fluently, then held a remarkable diving catch at deep square leg to oust Jason Gallian, whose innings of 61 did much to put Lancashire within sight of success. When he was out, they needed 109 from 15 overs. Paul Smith later held a stunning catch but Lancashire prevailed.Reuse content