Llanelli Scarlets will play Wasps in the inaugural Powergen Cup after the Welsh side won an enthralling semi-final at the Millennium Stadium.
Llanelli Scarlets (7) 27:
Tries: Dunlea, King, M. Jones
Cons: Hercus (3)
Pens: Hercus (2)
Bath (16) 26:
Tries: Crockett, Maddock
Cons: Malone (2)
Pens: Malone (4)
Chris Malone's penalties gave Bath a 16-7 advantage at half-time after Alex Crockett cancelled out Craig Dunlea's opening try for the Scarlets.
Joe Maddock's try stretched Bath's lead, but Mark Jones and Regan King tries put the Scarlets one point ahead.
Bath hit back with another Malone kick, but Mike Hercus' penalty clinched it.
Dunlea's opening try came either side of two Malone penalties as the match started at a frantic pace under the Millennium Stadium roof.
The New Zealand prop forced his way over under the post from a close-range ruck two after Alix Popham was stopped inches from the tryline.
Fly-half Hercus added the simple conversion, but missed a relatively straightforward penalty five minutes later to extend the lead.
Bath gradually began to dominate, and a fine three-quarter move brought their first try.
Former Stradey Park favourite Salesi Finau cut inside from the left wing and a scissor move sent Crockett clear.
Bath's Alex Crockett scored a fine individual try
The centre beat full-back Barry Davies will a neat chip-kick, and managed to ground the ball under pressure from Mark Jones.
Malone kicked the conversion and another penalty to give the English side a 16-7 half-time advantage.
Hercus' early penalty raised Scarlets hopes, but another inside pass from Finau freed centre Maddock to score in the left corner.
Malone maintained his impressive strike-rate by slotting the conversion, yet a pulsating match continued at a breakneck pace and Llanelli immediately cut the deficit with a converted try.
Hercus delivered the telling pass as King had enough pace to beat flanker Andrew Beattie on the outside.
Bath's problems worsened as winger Andrew Higgins was sin-binned and the fired-up Scarlets needed just two minute to make the advantage pay as Mark Jones came off his win charged over under the posts.
Hercus' conversion put the Scarlets ahead for the first time since the half hour at 24-23 with just over an hour to go.
The lead lasted a mere two minutes as Malone kicked another penalty, but Hercus kept his nerve to land another three points to give the Scarlets a one-point lead with eight minutes remaining.
Malone almost snatched the win with a last-ditch drop-goal, but his effort fell well short and the referee blew up after the Scarlets grounded the ball over their own tryline.
Bath coach Brian Ashton:
"We're bitterly disappointed we didn't win the game, but Llanelli's fightback in the second half swayed the balance their way.
"We played some good rugby in the first half but lost our way in the second by failing to be decisive and getting out of our 22.
"We tried to run everything and a side that plays one way become predictable."
Llanelli Scarlets captain Simon Easterby:
"We've come unstuck a few times in semi-finals in Europe, but we put a lot of effort into today.
"We gave 100%, dug deep and the reward is the win and we're delighted.
"We've showed we can mix it with the best, but we've got to remember we haven't won the tournament yet."
Bath: Perry; Higgins, Crockett, Maddock, Finau; Malone, Walshe; Stevens, Mears, Bell; Borthwick (capt), Grewcock; Beattie, Lipman, Feaunati.
Replacements: Abendanon for Finau (48), Delve for Grewcock (77), Short for Fea'unati (75).
Not Used: Dixon, Williams, Dunne, Loader.
Scarlets: B. Davies; M. Jones; Watkins, King, James; Hercus, Stuart-Smith; Dunlea, Rees, J. Davies; Afeaki, A Jones; Easterby (capt), G. Thomas, Popham.
Replacements: Byrne for M. Jones (77), Madden for Dunlea (67), Gravelle for Rees (52), Quinnell for Afeaki (72), D. Jones for A. Popham (74).
Referee: M Changleng (Gala)