Northern Diamonds booked a Rachael Heyhoe Flint Trophy knockout spot after hammering Thunder by 105 runs in their clash at Emirates Riverside. Diamonds put forward a brilliant effort with the bat as Bess Heath top scored with an unbeaten 78, but there were also half-centuries for Beth Langston and Sterre Kalis along with a score of 48 from Ami Campbell in their innings of 294 for 5.

Although Georgie Boyce offered resistance with a knock of 67, the chase always appeared too much for the visitors amid miserly bowling from Hollie Armitage and company. Katie Levick claimed four wickets, while Armitage notched two herself to allow the hosts to ease over the line ahead of a crucial contest next week against table-topping Southern Vipers.

Thunder won the toss and inserted the home side in cloudy conditions at Chester-le-Street. Armitage was unable to build on her impressive knock in Diamonds' win over Western Storm on Friday, picking out Natalie Brown at point off the bowling of Alice Dyson for only 7. Kalis calmed proceedings alongside Rachel Hopkins, producing a stand worth 47 for the second wicket.

Hopkins took her time to settle, and just when she appeared to be finding her rhythm Brown found her outside edge, allowing Eleanor Threlkeld to make a sharp grab. Kalis pressed forward in her innings and found the boundary with ease on her way to a fine half-century from 57 balls. The Netherlands international was dismissed a great catch by Sophia Turner at cover, but Campbell and Heath ensured the Diamonds maintained their momentum.

Campbell took the attack to Alex Hartley dispatching two straight sixes over the head of the left-arm spinner. The left-hander tried to go for another maximum to reach her half-century, but was caught on the boundary by Laura Marshall. But Heath and Langston launched an assault on the Thunder bowlers late in the innings, putting on a stand of 91 for the seventh wicket. Heath provided the platform before Langston powered a quick-fire fifty from 28 balls to usher Diamonds to a strong total.

The visitors made a measured start to their replay as Boyce found the boundary off the bowling of Ella Telford. Phoebe Graham entered the attack at the Finchale End to end the opening stand, removing Seren Smale for 12. Threlkeld and Daisy Mullan were unable to time the ball amid tight bowling from the hosts and paid the price with their wickets. Boyce held the key for the Thunder, and although she was dropped on 49 by Telford, she capitalised by reaching an 84-ball fifty.

The chase was all but over for the Thunder when Armitage removed Boyce for a solid 67 as she attempted to find the boundary, before the Diamonds skipper ran out Brown at the non-striker's end.

Thunder's required rate soared above 15 runs per over as the hosts continued their stranglehold of the contest, despite a stand worth 55 from Marshall and Laura Jackson. Levick notched late wickets to claim figures of 4 for 34 to ensure the hosts closed out a comfortable win and a place in the top three.