Having been on the wrong end of a 72 point thriller in their opening game against Benetton Treviso in Italy the previous weekend, it was vital the Scarlets gave their home fans something to shout about.
For a large part of the game they were shouting about the high error count that threatened to cost their side the game, but the 6,434 faithful roared with delight when victory was finally clinched.
For much of the frantic final few minutes it looked as though the try hat-trick from Fionn Carr was going to condemn the Scarlets to another defeat, yet they were able to snatch victory from the jaws of defeat in the end.
"The result is great, but we should never have to score 35 points to win a game at home. The performance certainly wasn't what we were expecting and out accuracy was appalling," said Scarlets coach Nigel Davies.
"We were terribly lose and the only time we showed any composure, and went through more than five phases, was when we scored the winning try. The onus will be very much on the players to sort things out in training this week."
Connacht came into the game having sat on top of the table for the first week following their big home win over the Dragons on the opening day of the season and quickly found themselves with a handy six point lead.
Ian Keatley hit the mark 25 metres out from the same spot with two simple penalties and the alarm bells were ringing early doors for the home side.
The recovery from that early deficit was sound from the Scarlets with 13 points in a five minute purple patch finally establishing their credentials as an attacking force. Two penalties from Stephen Jones wrapped around the first of Wales centre Jon Davies' brace of tries, but there was no time to celebrate.
From the re-start from Jones' second penalty, Connacht regathered and Carr was sent motoring over in the left corner. Keatley converted to level the scores, but his half-back partner Frank Murphy stupidly clothes-lined home full back
Andrew Fenby after he chipped over his head and Connacht had to spend the final five minutes of the first half with 14 men. That gave Jones the chance to conjure up a try for Regan king with a neat chip into no-mans land in the Connacht 22 as Davies picked up an off-loaded in one move.
Jones' conversion re-established the lead, but the scoreboard was locked once again five minutes after the break when Carr raced 60 metres to punish yet another home error.
Jones and Keatley, who kicked seven from seven for 18 points, swapped penalties before a brilliant break by Troy Nathan from half-way created the opening for Carr to race in for his hat-trick try.
A second yellow card for the visitors then gave the Scarlets the chance to hit back and no sooner had replacement prop Ronan Loughney headed to the sin-bin than Davies romped over for his second score.
Jones' conversion made it all-square again, but from the re-start the Scarlets coughed up another penalty to give Keatley an instant opportunity to regain the lead.
As the game moved into injury time the Scarlets kept hammering away, but it wasn't until they finally held onto the ball in the dying seconds that they finally cleared the way for Lamont's victory charge.
Scorers: Scarlets: Tries: J Davies 2, R King, S Lamont; Cons: S Jones 3; Pens: S Jones 3.
Connacht: Tries: F Carr 3; Cons: I Keatley 3; Pens: I Keatley 4
Scarlets: A Fenby; G North, R King, J Davies, S Lamont; S Jones, M Roberts (T Knoyle 56); P John (I Thomas 56), M Rees (captain, K Owens 75), R Thomas (P Edwards 75), L Reed, J Fa'amatuainu (D Day 81), J Turnbull, J Edwards, R McCusker.
Connacht: G Duffy; T Nathan, N Ta'auso (M Nikora 61), K Matthews, F Carr; I Keatley, F Murphy (captain, C Willis ); B Wilkinson (R Loughney 61, B Wilkinson 71-83), S Cronin, J Hagan, M Swift, B Upton; M McCarthy, R Ofisa (A Flavin 81), M McComish
Referee: Neil Paterson (SRU)