A fine kicking performance from Scarlets fly-half Owen Williams handed the hosts a 25-15 victory over Connacht at Parc y Scarlets.
Lock Joe Snyman scored the Scarlets only try - his first try for the region.
But the Welsh side found themselves out-scored two tries to one by Connacht who were indebted to scores from wing Daniel Poolman and lock Mike Swift at either end of the contest.
Connacht enjoyed a dramatic start with Poolman going over in the right corner after only 29 seconds latching on to fly-half Dan Parks' accurate cross kick, but Parks missed the conversion.
But following a break by centre Adam Warren the Scarlets got on to the scoreboard with a penalty from Owen Williams on five minutes.
Parks had the chance to restore his side's five-point lead but his 45-metre penalty shot rebounded off the right post. After soaking up a spell of pressure the Scarlets earned themselves a penalty which Williams kicked on 20 minutes to give the region a 6-5 lead.
But from Connacht's next attack Parks slotted over a drop goal to regain the lead for the Irishmen.
The lead changed hands for a third time with Williams landing his third penalty following a Connacht ruck offence, just before Parks missed a long penalty shot. But Parks' opposite number Williams converted one of two injury-time penalty attempts to give the Scarlets a 12-8 half-time lead.
The Scarlets eventually put some daylight between them and Connacht scoring 10 unanswered points.
First Snyman crashed over for a try converted by Williams, who then landed his fifth penalty as the region led 22-8. Before he left the fray Williams converted his sixth penalty.
But four minutes from time Connacht had the final say when replacement lock Mike Swift crashed over for a try converted by Miah Nikora.
But it was too little, too late for the Irishmen although they did have the consolation of knowing they had out-scored the Scarlets two tries to one.
Pens: Williams 6
Tries: Poolman, Swift
Drop Goal: Parks
Scarlets: 15 Gareth Owen, 14 Andy Fenby, 13 Nick Reynolds, 12 Adam Warren, 11 Kristian Phillips, 10 Owen Williams, 9 Aled Davies, 8 Kieran Murphy, 7 Josh Turnbull, 6 Rob McCusker (capt), 5 Johan Synman, 4 George Earle, 3 Samson Lee, 2 Emyr Phillips, 1 Phil John.
Replacements: 16 Kirby Myhill, 17 Shaun Hopkins, 18 Deacon Manu, 19 Jake Ball, 20 Lewis Rawlins, 21 Gareth Davies, 22 Aled Thomas, 23 Gareth Maule.
Connacht: 15 Tiernan O'Halloran, 14 Danie Poolman, 13 Eoin Griffin, 12 Kyle Tonetti, 11 Fetu'u Vainikolo, 10 Dan Parks, 9 Kieran Marmion, 8 Eoin McKeon, 7 Johnny O'Connor, 6 Andrew Browne, 5 Mick Kearney, 4 Michael Swift, 3 Nathan White (capt), 2 Jason Harris-Wright, 1 Brett Wilkinson.
Replacements: 16 Ethienne Reynecke, 17 Rodney Ah You, 18 Ronan Loughney, 19 Willie Faloon, 20 John Muldoon, 21 Paul O'Donohoe, 22 Miah Nikora, 23 Gavin Duffy.