Thunder scraped a thrilling one-wicket win against The Blaze at Trent Bridge as the hosts slumped to a fourth defeat in five in the Rachael Heyhoe Flint Trophy.
Chasing 175 to win, Thunder appeared to be cruising to their target at 89-0, with Seren Smale hitting a half-century.
But Smale (58) was part of a collapse which saw Thunder slump to 128-6 and then 161-9.
It was left to final pair Pheobe Graham and Hannah Jones to steer the visitors home in a thrilling finish.
Thunder chose to bowl first and 18-year-old England quick Mahika Gaur ousted the dangerous top order trio of Tammy Beaumont, making her first Blaze appearance of the season, Teresa Graves and South Africa international Nadine de Klerk to leave the hosts 52-3 in the 12th over.
It was 74-5 five overs later before skipper Kirstie Gordon steadied the ship with 43 from 82 balls, her best knock in nine years, before falling to Kate Cross.
Number nine Sophie Munro lasted 50 balls for her 19 before being run out as the Blaze recovered from 108-7 to reach 174, with Gaur finishing with 3-33 and left-arm spinner Jones taking 3-37.
It looked to be a straightforward chase for Thunder as Smale and England opener Emma Lamb put on 50 in the opening six overs and reached 89-0 in the 16th.
However, Lamb’s departure for 44 sparked a collapse which saw six wickets fall for the addition of just 39 runs and left the game in the balance, with left-arm spinner Gordon collecting 3-25 and off-spinner Lucy Higham 3-28.
Smale departed, bowled by Gordon, with victory still 47 runs away and, despite Sophie Ecclestone and Cross getting the chase back on track, Ecclestone and Gaur fell to Gordon in consecutive deliveries to leave the visitors on 146-8.
Cross stood firm for 15 and was the ninth wicket to fall with 14 runs needed but also with the spinners having used up their allotted overs.
However, Graham and Jones resolutely rotated the strike and hauled Thunder to the line with more than five overs to spare to go fifth and leave Blaze rooted to the foot of the table.
