Connacht took the spoils in a bruising Guinness PRO12 mid-table tussle at the Sportsground, as they defeated the Scarlets for the first time since September 2011.
Pat Lam's side scored 11 unanswered points in a rain-hit second half - a brilliant breakaway try from Matt Healy and two Jack Carty penalties - to seal a 14-8 success which cements their current top six position.
The Scarlets had led 8-0 after just three minutes, with fly-half Steven Shingler kicking a penalty and setting up an opportunist try for Harry Robinson.
However, the Welsh region, whose international players were sorely missed, failed to score thereafter. Carty cut the gap to 8-3 for half-time and Connacht's forwards decisively forced the issue after the break.
Lam spoke beforehand about the importance of building an early platform, but it was the Scarlets who surged ahead thanks to a Shingler penalty and winger Robinson's third-minute try.
Connacht failed to gather the kick-off and the Scarlets quickly setting up a lineout maul, with George Naoupu's infringement punished by Shingler's only three-pointer of the night.
Worse followed for the westerners as Carty allowed a kick to bounce in front of him and his opposite number Shingler swooped on it to send winger Robinson over to the left of the posts.
The Scarlets stand-off missed the conversion and a subsequent penalty, though, and good work from captain John Muldoon and Mils Muliaina preceded a response off the kicking tee from Carty.
Muliaina and Kieran Marmion got back to thwart Kristian Phillips following an eye-catching break from the left winger, and improved Connacht defence pressurised Shingler into a missed drop goal.
Bundee Aki's brilliant man-and-ball tackle on fellow Kiwi Regan King broke up a Scarlets attack, but errors blighted both sides' play as a hugely competitive first half came to a close.
A couple of noteworthy carries from Denis Buckley brought Connacht into scoring range early in the second period, and Carty clawed back another three points following a strong scrum.
Connacht conjured up a smashing try just moments later. The Scarlets lost ruck possession over halfway, Michael Kearney fed Dave McSharry whose well-timed pass released Healy - and the winger showed excellent pace to win the race to his own kick through.
Carty was unable to convert from the left touchline but Connacht continued to earn penalties at scrum time and they gained 15 metres from a monster maul towards the right corner.
As the rain came down Jacobie Adriaanse infringed a five-metre scrum, allowing Carty to make it 14-8 and man-of-the-match Aki hurtled into tackles to keep the Scarlets contained.
Frustratingly for Wayne Pivac's charges, they lacked the possession and territory to respond. After Carty pushed a drop goal effort wide and missed a late long range penalty, Connacht's pick-and-drive efforts wound down the clock to copper-fasten their first win in six meetings against the Llanelli outfit.