Alex Griffiths hit a six in the final over as Western Storm pulled off a dramatic one-wicket victory over Sunrisers in the Charlotte Edwards Cup at Chelmsford.
Needing 15 from the final over, Griffiths struck Grace Scrivens' first ball for a maximum and - needing three to win from the final delivery - an overthrow helped Storm steal an unlikely win.
Scrivens earlier made 56 from 42 balls in Sunrisers' 160-5 but with the ball she could not close out the final over.
Elsewhere, Northern Diamonds were bowled out for 92 to lose to Thunder, while Central Sparks and Southern Vipers both made it two wins out of two so far.
Scrivens was enjoying a dream night as she followed a fine innings by removing three of the top five in Storm's chase.
Katie George kept the innings alive with 34 in 23 balls but when she fell with 22 needed in 13 deliveries, the game looked over.
But 18-year-old Scrivens' evening turned sour as Griffiths held her nerve to guide Western Storm home and finished on 25 not out from 13 balls.
At Sale, Diamonds were chasing 149 to win after Georgie Boyce made 65 and Emma Lamb 50, but were 8-3 inside four overs of their reply.
Hannah Jones took 3-23 as they were finally bowled out in the last over.
Grace Potts took 4-36, including the final two wickets in consecutive balls, to help Sparks make it two wins from two as they beat Stars, the reigning champions, by 34 runs at Guildford.
Issy Wong's 45 and 40 from England wicketkeeper Amy Jones had helped build the Sparks' 170-6 before Stars were bowled out for only 136.
Vipers opened their campaign with a thumping eight-wicket win over Thunder on Saturday and it was also a comfortable win against Lightning at the Ageas Bowl.
Batting first, Maia Bouchier made 41 from 34 balls and England opener Danni Wyatt struck five boundaries in her 29 from 19 as the home side posted 155-5.
Lightning captain Kathryn Bryce made 54 in reply but there was only two other double-figure scores as they could only muster 124-8, Lauren Bell taking 3-12.