Mignon du Preez struck a scintillating, unbeaten half-century as Southern Vipers automatically qualified for the final of the Kia Super League with a 30-run victory against Yorkshire Diamonds at Arundel Castle.
Du Preez (50*) led the fightback from 78-4 as Southern Vipers posted 138-6 off their 20 overs, with Hayley Matthews (40) also striking her career best Kia Super League score.
In reply, both Arran Brindle (2-13) and Tash Farrant (2-23) took two wickets apiece as Yorkshire Diamonds were bowled out for 108 despite the best efforts of Katherine Brunt (42).
The hosts got off to a watchful start, with the opening pair of Suzie Bates & Matthews guiding their side to 12-0 after the opening three overs.
Bates (12) was starting to find her rhythm with a succession of quick boundaries, but was then dismissed by a smart catch from Sune Luus to reduce the hosts to 17-1.
Matthews started to find her feet, blazing 11 runs off the sixth over to guide her side to 36-1 at the end of the powerplay.
Southern Vipers continued to lose wickets, with Georgia Adams (5) ran out to end a promising innings on a good batting surface in West Sussex.
Despite this, West Indian batsman Matthews remained at the crease, crashing 16 runs off the ninth over to propel her side to 57-3 at the halfway stage.
She continued to find the boundary rope on a regular basis, whilst rotating the strike with Mignon du Preez, but her innings came to an end, with Alice Davidson-Richards (1-24) breaking the stand.
Du Preez and Brindle launched a counter-attack to move Southern Vipers into three figures in the 16th over, as they looked to finish the innings strongly.
South African du Preez led the fightback, smashing six quickfire boundaries as her side raced passed 100 and onto 125-4 with two overs remaining.
Du Preez then brought her maiden half-century for Southern Vipers in a brilliant 35-ball innings that swung the momentum back in the hosts’ favour.
Katie Levick (3-21) finished strongly for Yorkshire Diamonds, claiming the wickets of Brindle (11) and Farrant (1) as the Vipers posted 138-6 off their 20 overs.
Yorkshire Diamonds made a bright start in reply, with Chamari Atapattu smashing two sixes and two fours as the visitors raced to 27-0 off the opening three overs.
Brindle then came on to change the game with a superb fourth over, claiming the scalp of the England opener Lauren Winfield (7) before Luus (0) was ran out to reduce Yorkshire to 31-2.
The visitors fell to 34-3 when the dangerous Atapattu (21) was trapped in front by Bates (1-19) before Farrant dismissed Sophie Devine (0) in the very next over.
Debutant Tara Norris (1-18) took just four balls to pick up her maiden scalp for Southern Vipers, as their brilliant spell continued, as the visitors collapsed from 31-0 to 35-5 in the seventh over.
Brunt and Davidson-Richards dug deep and led the recovery, guiding their side to 54-5 at the halfway stage, but the run-rate continued to rise.
Brindle and Matthews (1-18) bowled economically in the middle-overs, but the Yorkshire Diamonds pair remained at the crease, moving the visitors along to 72-5 with seven overs remaining.
The partnership was ended by Brindle ), with Davidson-Richards (14) chipping it straight to du Preez, who could not be kept out of the game as the visitors fell to 78-6 at the end of the 14th over.
Brunt was still at the crease despite the loss of wickets and the England international, crunched a number of boundaries to move her side into three figures and keep them in the hunt for victory.
However, Brunt was ran out after an entertaining innings came to an end to leave Yorkshire Diamonds on 100-7 at the end of the 17th over.
The wickets started to tumble with Farrant dismissing Anna Nicholls (4) before Hollie Armitage (6) was ran out in the same over as the hosts suffered another collapse, moving from 100-6 to 107-9.
Matthews then returned to pick up the final wicket as Yorkshire were dismissed for 108 to seal a 30-run win for the Vipers, who automatically qualify for the final after Surrey Stars suffered a heavy 81-run defeat to Loughborough Lightning at the Oval.