Teenager Grace Scrivens and Ariana Dowse both hit maiden List A centuries in a 200-run partnership to set Sunrisers on the way to victory over The Blaze in the Rachael Heyhoe Flint Trophy.
Hosts Blaze are guaranteed a place in the final but slipped to a fourth defeat in five at Loughborough, despite a first hundred from Georgie Boyce.
Southern Vipers saw off South East Stars by 58 runs to leapfrog them into second place with one game remaining, putting them in pole position for a semi-final eliminator.
Elsewhere, Northern Diamonds defeated Thunder and Central Sparks beat Western Storm to keep their own top-three hopes alive.
Sunrisers themselves could yet gatecrash the semi-final eliminator, but need a win in their final game at Diamonds and other results to go their way.
Dowse, 22, hit 13 fours and a six in her 110-ball 105, with England Under-19 international Scrivens, who took her aggregate in this year's competition to 387, making 107 from 136 deliveries with nine fours.
Their 37-over partnership was the biggest for any wicket since the 50-over competition launched in 2020.
"That's three wins in a row and to beat The Blaze, who are top of the table, is really good for us," said 19-year-old Scrivens.
"I'm really happy with my own performance in getting that first hundred. And Ariana batted brilliantly in that partnership we put together - she has only just come into the side but she has fitted in superbly from the off, and Eva Gray bowled excellently for her 4-31.
"If we could qualify it would be amazing but we are just taking it game by game, looking to make it four from four and seeing where we are."
Eve Jones (84) and Maddy Green (64) scored half centuries as Central Sparks kept their hopes of a place in the knockout stages alive with a seven-wicket win over rock-bottom Western Storm at Taunton.
Sparks go into their final fixture against South East Stars at Edgbaston on Saturday in the knowledge the winner will progress.
Aylish Cranstone made 69 for Stars in Southampton but they were all out for 196 in reply to Vipers' 254, with Linsey Smith hitting 51 for the hosts and then claiming 3-34.
Lauren Winfield-Hill, leading run scorer in the competition, made 89 as Northern Diamonds were bowled out for 196 at Sale, with Olivia Bell taking 4-32 from 10 overs for Thunder.
Second-bottom Thunder were ousted for just 148 in reply with Katie Levick claiming 4-28.