Southern Vipers were crowned the first Kia Super League champions as veterans Sara McGlashan and Lydia Greenway held their nerve in a tense run chase against Western Storm.
The Vipers had finished top of the qualifying table and seemed on course for a comfortable win on Finals Day in Chelmsford as their captain Charlotte Edwards shared an opening stand of 78 with Suzie Bates in reply to a Storm total of 140 for five.
Storm, who had beaten Loughborough Lightning in the first game of a double header to secure their place in the final, hit back by dismissing both openers in the space of three overs, with Bates brilliantly run out by Fran Wilson for 52.
But Greenway joined McGlashan in an unbroken fourth-wicket stand of 39, and drove the winning boundary wide of mid-off with seven balls to spare.
Arran Brindle was an unlikely bowling star for the Vipers. The 34-year-old allrounder from Yorkshire came out of retirement for the KSL, and took two for 15 from her four overs including the key wicket of West Indies allrounder Stafanie Taylor – all while wearing her Vipers cap.
Storm’s total of 140 for five had been built around a canny half-century from their New Zealand wicketkeeper Rachel Priest.
She shared an opening stand of 74 inside 11 overs with Taylor, but the Storm started to lose momentum after Taylor had lofted Brindle to Edwards at mid-off.
Priest fell for 57 off 55 balls off the bowling of her compatriot Bates, coolly held on the boundary by Greenway, and although Wilson and Georgia Hennessy added some handy late runs, they did not quite have enough.
Edwards signalled her intent with a rare straight six, and Bates showed why she was named the outstanding female cricketer in the world by Wisden earlier this year by reaching a 43-ball half century with seven classical boundaries.
Kia Super League Semi Final: Western Storm charge into the Kia Super League Final!
Western Storm overcame a late wobble against Loughborough Lightning to reach the Final of the Kia Super League, and a meeting with the Southern Vipers.
The Storm, who were formed last winter by a groundbreaking partnership between Somerset, Gloucestershire and the University of Exeter, seemed to be cruising to victory when they pulled level with Loughborough’s total of 124 for seven with eight balls remaining.
But Ellyse Perry, the Australian star who had already made a superb unbeaten 64 and taken a spectacular boundary catch for the Lightning, then took her first wicket.
And when Heather Knight, the Storm and England captain who had steered her team to the brink of victory with 52 off 43 balls, chipped a catch to mid-off, Western nerves were starting to jangle.
But Georgia Hennessy stayed cool to slap a full toss from Sophie Devine for the winning boundary, sealing a five-wicket win with three balls to spare.
The result means Knight will face her predecessor as England captain Charlotte Edwards in the Final, after the Vipers booked the first place in the title-deciding game, which starts at 3pm, by finishing top of the qualifying group.