A superb three try blitz either side of half-time saw the Scarlets emerge with a 24-21 triumph over Connacht at the Sportsground.
Craig Ronaldson's three penalties to Aled Thomas' one had given the Irish province a 9-3 lead before Frazier Climo touched down late on in the first period for the visitors.
Further tries from Kirby Myhill and Gareth Davies within five second half minutes effectively sealed the win for the Welsh region, although Matt Healy and Jason Harris-Wright narrowed the gap and secured a losing bonus-point.
With the team sitting in mid-table going into this game, Simon Easterby's men needed a victory against the bottom placed Pro12 team to have realistic ambitions of reaching the play-offs.
However, they struggled in the opening stages and Ronaldson kicked Connacht into a 6-0 lead after nine minutes.
Although Thomas reduced the arrears with a penalty of his own, Jacobie Adriaanse was sin-binned for the Llanelli-based outfit and the hosts' stand-off added another three-pointer.
As the half neared its conclusion, the Scarlets suddenly came to life. Climo's converted try took them into the lead and they carried that momentum into the second half.
Myhill extended the visitors' advantage before Davies completed an excellent spell with another touchdown for Easterby's side.
But to their credit, Pat Lam's team showed impressive resilience to come back. Healy gave them hope with a try and, after Aaron Shingler was sin-binned, Harris-Wright further increased the pressure with a second score.
However, despite Gareth Owen's yellow, the Scarlets held on.
Tries: Healy, Harris-Wright
Pens: Ronaldson 3
Tries: Climo, Myhill, G. Davies
Cons: A. Thomas 3
Pen: A, Thomas
Yellow cards: Adriaanse, Shingler. Owen
Connacht: 15 Gavin Duffy, 14 Darragh Leader, 13 Eoin Griffin, 12 Dave McSharry, 11 Matt Healy, 10 Craig Ronaldson, 9 Kieran Marmion, 8 Eoghan Masterson, 7 Jake Heenan, 6 Aly Muldowney, 5 Craig Clarke (capt), 4 Michael Swift, 3 Nathan White, 2 Sean Henry, 1 Brett Wilkinson.
Replacements: 16 Jason Harris-Wright, 17 Ronan Loughney, 18 Rodney Ah You, 19 Mick Kearney, 20 George Naoupu, 21 Frank Murphy, 22 Dan Parks, 23 Fionn Carr.
Scarlets: 15 Gareth Owen, 14 Frazier Climo, 13 Gareth Maule, 12 Adam Warren, 11 Nic Reynolds, 10 Aled Thomas, 9 Gareth Davies, 8 Sione Timani, 7 Josh Turnbull, 6 Aaron Shingler, 5 George Earle, 4 Jake Ball, 3 Jacobie Adriaanse, 2 Kirby Myhill, 1 Phil John (capt).
Replacements: 16 Darran Harris, 17 Shaun Hopkins, 18 Ian Jones, 19 Jo Synman, 20 Dan Thomas, 21 Aled Davies, 22 Josh Lewis, 23 Kristian Phillips.
Venue: The Sportsground
Referee: Matteo Liperini (Italy)
Assistant referees: Paul Haycock (Ireland), Olly Hodges (Ireland)