Sunrisers 253 (Gardner 61, Scrivens 51, Jones 4-50) beat Thunder 224 (Lamb 48, Munro 5-25) by 30 runs

Sophie Munro produced a stunning spell on her Rachael Heyhoe Flint Trophy debut for Sunrisers to keep them in the top two with a tense win over Lancashire Thunder at Chelmsford.

Seamer Munro, on loan from The Blaze, captured three wickets in four balls - including the key scalp of ex-Sunrisers batter Naomi Dattani - as she wrapped up her side's first victory over Thunder in any format with figures of 5 for 25.

Dattani's knock of 36 seemed likely to steer Thunder past the home side's total of 253, which might have been higher but for a middle-order collapse after skipper Grace Scrivens (51 from 54 balls) and Jo Gardner (63 from 78) had shared an opening stand of 94.

Sunrisers then lost six wickets for 52, with left-arm spinner Hannah Jones returning four for 50 to become the tournament's joint highest wicket-taker with 14.

Even with drizzle and dark clouds hovering above the ground, Scrivens chose to bat after winning the toss and, despite some early swing for left-armer Tara Norris, the home side built steadily. They reached 48 in the 10th over before the drizzle developed into heavier rain and, once the players returned after almost an hour's delay, the contest was reduced to 48 overs a side.

Scrivens looked nicely set, taking successive fours off former team-mate Dattani as she advanced to her 50 only to be bamboozled soon afterwards by Fi Morris, with Ellie Threlkeld completing a stumping.

Gardner might have gone the same way when she misjudged a ball from Sophie Morris, who bowled consistently to finish with 2 for 38, but the opener survived to post her first half-century of the tournament.

Having pumped Fi Morris for two leg-side sixes, Gardner's pursuit of a third proved costly as Katie Mack clasped the catch just inside the rope to trigger Thunder's fightback. Fi Morris was also the architect of Jodi Grewcock's downfall, deflecting Cordelia Griffith's full-blooded drive onto the stumps to run her out and Jones then weighed in by having Flo Miller and Amara Carr leg before sweeping in the same over.

Clean hitting by Mady Villiers took her to 35 from 26 with back-to-back boundaries off Jones but, when she was clean bowled by the next delivery, that appeared to signal an end to Sunrisers' hopes of posting 250. However, the visitors surprisingly returned to Dattani and Phoebe Graham's expensive medium pace and last pair Munro and Kate Coppack took advantage, adding a valuable 32 to set a slightly adjusted target of 255.

Thunder openers Emma Lamb and Seren Smale looked comfortable at the start of the chase, working the ball around with ease and ticking along at above five an over in their stand of 63 from 69. Grewcock finally broke the partnership when Villiers' diving catch at midwicket accounted for Smale and the spinner also collected the scalp of Lamb, caught top-edging a paddle two short of a deserved half-century.

Mack - who registered a hundred in Thunder's win over Sunrisers earlier in the tournament - looked on course for another match-winning knock with 33 from 42 until Eva Gray trapped her in front.

With Threlkeld and Danni Collins both run out after mix-ups, the burden fell on Dattani's shoulders - and she survived a couple of close calls against Scrivens, with a pull fumbled at midwicket and a stumping chance going begging.

But Munro's sixth over proved decisive as she dismissed Norris and Graham in successive balls and had Dattani caught behind before Jones holed out to long-off to round off the win with 16 deliveries to spare.