The Ospreys made the Scarlets wish they had stayed at home with a crushing 50-24 Boxing Day victory at Liberty Stadium.
The Scarlets were brought crashing down to earth after their Heineken Cup success in Toulouse as they were blitzed with a five try display by the Ospreys.
After the drama of their 41-34 win at Toulouse in the Heineken Cup ten days ago, the Scarlets were put to the sword in the Magners League clash as the Ospreys bounced back from their 30-24 defeat at Cardiff Blues just four days before.
The Scarlets lost chief playmaker Stephen Jones with back spasms in the warm-up, but the hosts were powerless against a rampaging Ospreys side with rising star James Hook in sublime form and claiming a personal twenty-three point haul in the No.10 shirt in front of a bumper 20,500 crowd.
The hosts raced out to a 13-0 lead when fullback Lee Byrne broke the defence to leave No.8 Ryan Jones to crash over. Hook landed the conversion and kicked two penalties before the Scarlets finally sprang into life.
Their fly half, Thomas, chipped the defence and with a posse of midfielders chasing the ball into the dead ball area, Ospreys scrum half Justin Marshall slapped the ball away, leaving referee Nigel Owens no option but to award a penalty try and show the ex-All Black a yellow card.
Thomas landed the conversion but Hook was in sublime kicking form with three more penalties before Thomas put the Scarlets back into contention with a penalty deep in first half injury time to make it 22-10 at half-time.
The game was effectively ended as a contest just after the break when Marshall's interception fed wing Nikki Walker who sprinted clear for his side's second converted try.
The Scarlets replied with Dwayne Peel darting over for a converted try to pull the scores back to 29-17, but Lee Byrne carved a huge hole in the crumbling defence for his side's third try and Hook's third conversion.
Second half replacement lock Lyndon Bateman barged his way over for his side's fourth try late on which gifted the Opsreys the bonus point. The fifty point mark was broken when substitute flanker Andy Lloyd crashed over under the posts in injury time and Hook's replacement Shaun Connor landed the conversion.
Gavin Evans converted try on the final whistle just about spared the Scarlets' blushes.
Glyncoch have had a remarkable past couple of seasons, having lost just once in the last two seasons. Their fine form has been capped by claiming the South Central Division 5 crown of the SWALEC League.
With two rounds of the HSBC Sevens World Series remaining, Wales head coach Paul John has sprung a few surprises for this week's penultimate round in Glasgow. And there's still plenty to play for with World Cup spots on the line.