The club's cup campaign had threatened to stall on the opening day after a controversial try from Andy Fenby gave the Welsh region a first half lead.

But Warriors battled back in the second half before pulling clear in then dying minutes.

Replacement Ben Howard cruised over to put the teams back on level terms before the big man Semisi Taulava crashed over for the lead.

Jake Abbott secured the win before, in a dramatic finale, Neil Best bashed his way over the whistwash for the extra point that sends Warriors to the top of the pool standings.

Warriors went on the attack in the opening minutes with Jake Abbott, Dean Schofield and Jon Clarke making yards before Scarlets turned over ball at the breakdown and forced Chris Pennell to race back and clear.

Visiting full back Fenby made yards before Chris Jones picked up a loose ball and galloped down the middle to win Warriors a penalty. Joe Carlisle made a sweet connection and drilled the kick over for the lead.

A penalty at the scrum allowed Scarlets to regroup and Fenby again made inroads before Owen Williams flicked out of the tackle to release Adam Warren. Ball was knocked on but play went back for a penalty for not rolling away and Williams drew the teams level.

Another penalty at scrum time gave Williams the chance to send his team further ahead.

Shaun Hopkins high tackle on Pennell allowed Warriors play with width on free ball and when Scarlets infringed Carlisle leveled up mattes from wide left.

Alex Grove led a quick counter attack down the left flank to earn territory before Scarlets struck with a huge slice of fortune.

A break down the right saw Kristian Phillips kick ahead into space for Fenby who looked to pick up and score but appeared to knock on as he went to ground the ball. However, the try was awarded by referee Tim Wigglesworth and Williams added the extras.

James Currie produced a huge hit on scrum half Aled Davies to drill him backwards as Scarlets looked to work around the fringes before Andy Short swooped to win a penalty for holding on in conjunction with newcomer Richard de Carpentier.

Williams missed another kick at goal as his kick drifted left of the uprights while Carlisle produced a huge clearing boot to release some of the pressure mounting on Warriors.

Carlisle turned down a long range shot at goal to go for field position, after Dan Thomas was penalised for not releasing Chris Jones after he rumbled down the middle.

Tempers then flared after Jones was taken out in the lineout and when order was restored Joe Snyman and Schofield were both yellow carded as Scarlets were awarded the penalty.

Another penalty at the lineout, this time against Jones for a push, gave Williams a long range shot at goal but his effort never threatened the posts as it dropped short.

One final attempt from Warriors to strike before half-time saw Short and Clarke both make yards before Jake Abbott side stepped one tackle to drive towards the posts. Pennell and Cowan also hit contact hard, but ball was spilled and possession lost.

Warriors made two changes at the break as Andy Goode and Ben Howard entered the game.

Fenby was nearly away for a second score after Scarlets picked off a loose pass. Ball worked neatly back in field before Worcester disrupted play at the breakdown to turnover ball.

Carlisle looked to spark Worcester into life with a show and go and side step into space while Goode tried to pick out fellow replacement Howard with a cross field kick but could only find the hands of Warren.

Tempers flared again after a tackle by Currie on Lee Williams and again referee Wigglesworth gave the penalty to Scarlets. Up stepped Owen Williams but again his effort was short.

Pennell and Goode linked down the right before Carlisle flicked out of the tackle to George Porter and Grove as Warriors looked for an opening.

Carlisle kicked to the corner to set up a drive and the forwards battled up close before Arr lost control as he went for the line with a penalty already in the bank.

Worcester kicked for the corner and after driving up close through Shervington and Abbott the ball was spun wide. Goode looked as if his floated pass would be picked off, but the ball fell backward and found Howard who dived in. Carlisle added the difficult extras to level the teams.

Owen Williams should have nudged Scarlets back ahead with 20 minutes left, but his relatively simple kick was badly off target to the left.

Hill beefed up his pack with Neil Best, Ceri Jones and Semisi Taulava all introduced in the final 25 minutes.

Worcester were beginning to control possession and territory as Taulava punched holes down the middle before slick hands nearly send Short in only for a foot in touch to deny him.

The pressure was building, though, and seconds later a quick tap penalty from Arr, after a bent lineout throw, fed Taulava and he crashed through men from short range to score. Carlisle added the extras for a 20-13 lead.

The home forwards were now beginning to turn the screw and hurt Scarlets at the scrum to win a penalty that Worcester again opted to kick to the corner. This time the drive never looked like being stopped as Abbott was the man to touch down.

Warriors were now hunting the try bonus point but it was Scarlets who struck back as Kristian Phillips secured a long range score as he hacked ahead to touch down.

But there was still time for one last attack as Chris Jones pounced on a loose pass and Worcester broke at pace with Shervington just stopped short before he popped a pass to Best to secure the vital extra point.

Timeline:

04m Carlisle p 3-0

07m Williams p 3-3

12m Williams p 3-6

14m Carlisle p 6-6

17m Fenby t Williams c 6-13

55m Howard t Carlisle c 13-13

68m Taulava t Carlisle c 20-13

73m Abbott t Carlisle c 27-13

77m Phillips t 27-18

80m Best t Carlisle c 34-18

Warriors: 01 George Porter (Ce Jones 55), 02 Ed Shervington, 03 James Currie, 04 Dean Schofield, 05 Chris Jones, 06 Richard de Carpentier (Best 55), 07 Jake Abbott, 08 Blair Cowan (Taulava 65), 09 Jonny Arr, 10 Joe Carlisle, 11 Andy Short, 12 Jon Clarke (Goode 40), 13 Alex Grove, 14 Nikki Walker (Howard 40), 15 Chris Pennell

Replacements: 16 Ollie Hayes, 17 Ceri Jones, 18 Rob O'Donnell, 19 Semisi Taulava, 20 Neil Best, 21 Ollie Frost, 22 Andy Goode, 23 Ben Howard