Bath's European Champions Cup quarter-final hopes suffered a crushing setback as the Scarlets cut them to shreds at the Recreation Ground.
Bath, though, are facing being frozen out of the last-eight picture after their red-hot opponents ran in tries by lock Tadhg Beirne, wing Paul Asquith and Wales worldwide centres Scott Williams and Hadleigh Parkes.
A Dan Jones penalty made it 22-0 to the visitors at the break, and it soon got worse for Bath as Rhys Patchell's grubber was superbly finished off by Scott Williams for the bonus point.
Welcome to this evening's live blog of Bath versus Scarlets. The Scarlets, meanwhile, will battle it out with Toulon in what is sure to be a fascinating climax to the group stage.
Bath dominated initial territory, but they suffered a major injury blow when their Wales global fly-half and former Scarlets number 10 Rhys Priestland limped off.
Scarlets' four tries earned them a bonus point which puts them four points clear of Bath at the top of Pool 5. Kick-off is just over 50 minutes away at 7.45pm. It is all there for Ken Owens side and their magnificent fans will have a huge role to play.
Jones added the conversion as Scarlets served immediate notice of their renowned attacking prowess that drove them to last season's Guinness PRO12 title.
Pre-match omens also, look to be in Bath's favour as 21-year-old wünderkind flanker Sam Underhill returns to action for the first time after suffering a concussion in England's autumn global victory against Australia.
Scarlets number eight John Barclay's penalty indiscretion - he roamed offside to halt Bath scrum-half Chris Cook just two metres from his own line - gave referee Jerome Garces little option but to sin-bin him.
The first score in the second half was going to be vital and there was no let-up from the Scarlets.