Northern Diamonds 229 for 8 (Gunn 50*) beat Lightning 226 (S Bryce 51) by two wickets
Northern Diamonds maintained their 100 per cent record in the Rachael Heyhoe Flint Trophy after veteran former England star Jenny Gunn rolled back the years to drag a victory from what had looked like a losing position at the Fischer County Ground, Leicester.
Chasing 227 to win, Diamonds appeared to be heading for defeat when they slipped to 119 for 7 in the 30th over, still well short of the required rate and with wickets running out.
But 34-year-old Gunn, who played for Lightning in the Kia Super League in 2018 and 2019, teamed up with another experienced campaigner in Beth Langston to add 81 in 15 overs for the eighth wicket before fellow World Cup-winner Langston fell for 37.
That still left 27 required but Gunn stayed on to complete a 72-ball half-century before Phoebe Graham struck the winning boundary with seven balls to spare.
Diamonds had beaten the Loughborough-based side by nine runs on the back of England star Nat Sciver's century at the Emirates Riverside last Monday but even with Sciver and international teammates Katherine Brunt, Lauren Winfield and Linsey Smith all absent they proved too strong again.
After being made available for the opening two matches in the competition, the England quartet have joined the national squad ahead of the series against West Indies at Derby later this month. Lightning lost opener Tammy Beaumont and left-arm spinner Kirstie Gordon for the same reason.
Scotland wicketkeeper-batter Sarah Bryce made her third consecutive half-century and there were useful runs from Yorkshire-born Teresa Graves and Abbey Freeborn as Lightning made 226 despite not batting out their full 50 overs.
Having won the toss, Diamonds opted to bowl first but saw the home side begin positively, Bethan Ellis taking well to the responsibility of opening in place of Beaumont. She and Bryce put on 51 before they were parted in the 10th over as leg-spinner Katie Levick entered the attack to have Ellis leg before sweeping.
Diamonds had by then suffered a setback when Graham, who had taken the new ball alongside Langston, was ordered out of the attack after four balls of her fourth over, having twice been no-balled for full tosses above head height. Bryce, on 15, was caught off the second but allowed to continue her innings.
Kathryn Bryce could not keep her sister company long before she was bowled through the gate by former Lightning teammate Gunn but Freeborn started with a flurry of aggressive hits and set the tone for a partnership with the younger of the Bryces that added 56 for the third wicket before Bryce, having completed her third half-century of the competition, hit a Hollie Armitage full toss straight to deep mid-wicket.
Freeborn chopped on to Armitage's leg spin and Lucy Higham gave a simple return catch to seamer Alex MacDonald as Diamonds began to made inroads at 139 for 5 but then an excellent, enterprising partnership between Teresa Graves and Nancy Harman added 58 for the sixth wicket to put Lightning in reach of a competitive score.
Harman fell for 21 when she top-edged an attempted pull off Langston and Graves, dropped on 22, went on to reach 37 before she was leg before sweeping Gunn. Both players had recorded their highest scores in women's List A cricket. Three of Lightning's last four batters were making their competition debuts but only Leah Kellogg, run out as the non-striker, was unable to contribute.
Lightning then made an excellent start with the ball, seamer Kathryn Bryce conceding only one scoring stroke in her first three overs before Rachel Hopkins, the Durham batter making her Diamonds debut, was leg before pushing at a ball from Kellogg. Netherlands international Sterre Kalis was then judged leg before to a Bryce yorker. Diamonds did not pick up a boundary until Ami Campbell, another Durham player making her first appearance, dispatched Bryce for two fours in the ninth over and at 27 for 2 from 10 overs, the visiting team were well off the pace.
Armitage and Campbell added 55 for the third wicket but when the former was caught by Ellis, running in from the cover boundary, for 30, Diamonds were still well behind the required rate at 62 for 3 in the 19th over, by which point Lightning were in three figures. The wicket was a first for 20-year-old Northants all-rounder Alicia Presland on debut, having earlier seen Campbell dropped on 18.
Campbell registered the match's first six when she lofted a Higham full toss over the legside boundary and added a second when she clubbed Harman's leg-spin over long on, following up with four through midwicket as she tried to up the scoring rate. It was a short-lived effort, however, Ellis safely pouching another catch in the deep as Harman claimed her scalp for 41. At the halfway stage, Diamonds were still 120 short of their target at 107 for 5, Higham having found a way through Layla Tipton's defences in the previous over.
Higham bowled MacDonald and added a third scalp when Grace Ballinger took an easy catch off a Bess Heath miscue, at which point Diamonds still needed 98 more runs with only three wickets in hand.
But Gunn and Langston drew on their years of experience to turn the tables in Diamonds' favour, rotating the strike superbly and relentlessly finding the gaps in the field. A delighted Harman eventually trapped Langston in front but Graham and Gunn kept their nerve to complete the win.