Southern Vipers 145 for 5 (Bates 37) beat Loughborough Lightning 143 (Bates 3-22) by five wickets
Southern Vipers overcame a mid-innings wobble to edge past Loughborough Lightning and advance to the final of the Kia Super League in a nerve-jangling run chase at Hove.
But Loughborough spinners Sarah Glenn and Kirstie Gordon both struck in the middle overs to cause a hiccup and, as scoring became harder, only a crucial 22-run stand for the sixth wicket snuck the Vipers over the line and into the final.
"That was probably our best bowling and fielding performance of the tournament, and that set us up really," said Tammy Beaumont, the Vipers captain. "Danni and Suzie were exceptional in the powerplay. Danni is seeing it beautifully at the moment and Suzie is so experienced and then the middle order managed to see us home.
"We did so well with the ball. At one stage I thought we were going to be chasing 160 on what was a good wicket so to keep them to 143 was an outstanding effort."
Loughborough's attack laid claim to being the best in the competition when at full strength, but they were two bowlers short and it showed in a ragged powerplay. Kathryn Bryce (Scotland) and Hayley Matthews (West Indies) were both on international duty, and Shabnim Ismail, the overseas replacement fast bowler, missed the final group game and was unavailable as a result.
Ismail had originally been reported as unavailable due to visa problems, though according to Kate Cross, the Lancashire seamer on Test Match Special, they were largely of her own making: as it turned out, she had failed to apply for one.
It meant that Lightning were at least one bowler light, and when Wyatt and Bates decided to attack early on, they had few answers. Wyatt thrashed 19 off the second over, bowled by Jenny Gunn, and Bates followed suit as the pair put on 71 in the powerplay alone.
Quick wickets then pegged the Vipers back. Gordon bowled Bates with a delivery that was little short of a slow left-armer's dream, pitching on middle and spinning away from the bat to hit the top of off, before Wyatt was smartly stumped by England opening partner Amy Jones off Glenn's legspin.
Beaumont cut a frustrated, busy figure in her innings of 24, which also accounted for Maia Bouchier via a sloppy run-out, and after slashing four boundaries she chopped a Gunn slower-ball onto her stumps to leave the Vipers reliant on their lower-middle order.
Fi Morris struggled for timing in a scratchy, 16-ball 7, and Paige Scholfield and Amanda-Jade Wellington endured a nervy couple of overs where they could only scrap singles and the Lightning turned the screw. But Wellington's reverse-swept four off Glenn left them needing single figures, and Scholfield then charged down to deposit a length ball for another boundary over midwicket to seal the win.
Loughborough's innings of 143 was a frenetic affair, which jagged and veered rather than ebbing and flowing, and looked not far short of a par score on a wicket that offered something for the spinners.
Lauren Bell, a tall, wiry seamer who bowled with good pace and found prodigious swing, struck twice early. First, Jones - who had put a miserable Ashes series behind her by scoring 300 runs at 37.50 in the tournament - was perhaps fortunate to survive a convincing lbw appeal, before attempting to ramp a ball that moved in from outside off and succeeding only in playing it onto her off stump.
Then Bell struck again inside the powerplay to remove the dangerous Chamari Atapattu, trapping her lbw from around the wicket. While Bell is still a raw talent, as evidenced by the five wides and two no-balls she bowled, the makings of a future England player are there for all to see. She touched 70mph, and has regularly been part of their academy squads - at 18, she has a bright future.
Skipper Georgia Elwiss led the rebuilding job alongside Georgia Adams after the powerplay, and the pair added 55 in 6.1 overs, but when Elwiss flicked a Tash Farrant ball out to Wyatt at midwicket, she decided to take on one of England's best fielders and was duly run out coming back for a second run.
From there, things only got more frenzied. Mignon du Preez's international career has seen her play the role of accumulator, but she has struck at comfortably over 140 this season, and whacked a pair of sixes before holing out to Wyatt to end a tumultuous 11-ball innings of 21.
Gunn and Abigail Freeborn both did their best to keep things moving, but Bates cleaned up the tail in her final over, with Wyatt claiming her third catch at deep midwicket before Gordon's stumps were rearranged.
Western Storm did the double over both sides in the group stage, and will be confident of getting past the Vipers in the final, but flashes of form from Wyatt and Bates will have made it clear that they will need to strike early with the ball.
Matt Roller is an assistant editor at ESPNcricinfo. He tweets at @mroller98