A half-century by Michaela Kirk and four wickets for Teresa Graves helped Lightning to a second victory in the Rachael Heyhoe Flint Trophy as bottom-of-the-table Sunrisers slumped to a fourth defeat from four matches.

Naomi Dattani hit 65 and Kelly Castle 52 as Sunrisers posted 206 for 9 after opting to bat first at Loughborough University's Haslegrave Ground, seamer Graves taking 4 for 39. But Lightning chased down their target with almost 10 overs to spare with South African-born batter Kirk hitting nine boundaries, sharing partnerships of 57 with Sarah Bryce and 47 with Kathryn Bryce.

Abbey Freeborn then struck seven fours in a 48-ball 44, her partnership of 51 with Sonia Odedra effectively sealing the win. Freeborn was caught at midwicket with just two still needed before Graves hit the winning boundary.

Always ahead of the required rate, Lightning were 47 without loss in the Powerplay. Sarah Bryce was caught at backward point off Castle's medium pace but she was Lightning's only casualty in scoring 100 from the first 20 overs.

They suffered a double setback when Kirk and Kathryn Bryce fell in consecutive overs to offspinners Katie Midwood and Alice Macleod, Kirk trapped leg before sweeping before Bryce was bowled. But Freeborn and Lucy Higham added 48 for the fourth wicket, bringing the requirement down to 52 from 20 overs, before Higham was lbw to Castle sweeping.

Sunrisers were 31 for 3 after their Powerplay overs. Seamer Sophie Munro bowled Grace Scrivens off an inside edge and had Amara Carr well caught by Freeborn at slip, before left-arm spinner Kirstie Gordon took her ninth wicket of the competition so far, trapping Alice Macleod leg before.

Lightning captain Kathryn Bryce conceded only seven runs in her first six overs. Once she took a rest, however, runs came more easily as Dattani and Cordelia Griffith added 60 for the fourth wicket before the latter hit straight to mid-on as Graves made the breakthrough.

Dattani and Castle put on 87 in 17 overs for the fifth wicket, Dattani completing her half-century off 82 balls with five fours before clearing the rope off Lucy Higham's offspin for the only six of the innings. But Dattani was bowled attempting to sweep Yvonne Graves's offspin, sparking a late collapse as Sunrisers lost five wickets for 18 runs in six overs, three of them to Graves.

She dismissed Jo Gardner and had Gayatri Gole in the space of three balls before Castle played round one to be leg before, and Bryce picked up a deserved wicket when Freeborn held a good low catch at mid-on to remove Katherine Speed.