Scarlets produced a stirring second-half display to claim a second United Rugby Championship win of the season in a pulsating Welsh derby clash at Parc y Scarlets.

With a crowd of eight and a half thousand providing the extra man, Scarlets overcame the first-half dismissal of No. 8 Sione Kalamafoni to stun the Dragons and claim a 33-17 victory.

Leigh Halfpenny enjoyed a faultless evening with the boot, landing an 18-point haul, while Dane Blacker, Steff Evans and Johnny McNicholl crossed for tries.

The Scarlets trailed 17-16 at the break after losing talismanic No. 8 Kalamafoni - the side’s fourth red card of the season - for an altercation with opposite number Ross Moriarty.

But down to 14 men, the home side produced a performance packed with guts, passion and plenty of style to see out the win.

Led out by Dane Blacker and Sam Lousi on their 50th appearances, the Scarlets started impressively. Kalamfoni was denied a try because of a knock-on in the build-up, then Steff Evans almost pounced on trademark chip and chase.

Instead, they had to be content with two Halfpenny penalties.

JJ Hanrahan pulled three points back for the Dragons, then former Scarlet Angus O’Brien raced over following a break from wing Rio Dyer.

Scarlets responded in style with slick hands from the backs sending Steff Evans over for a superbly-crafted try, converted by Halfpenny.

Then, on 32 minutes, came a moment that saw tempers flare and two players sent from the field by referee Ben Whitehouse - Kalamafoni for punching Moriarty and the Dragons back-rower for his part in the scrap.

From the ensuing penalty, Dragons were back in front with scrum-half Lewis Jones sniping over from a line-out drive. Hanrahan added the extras.

A Halfpenny penalty reduced the arrears to a point at half-time, but few in the crowd could have anticipated what was to follow.

Another Halfpenny success put the Scarlets back in front early in the second half, then pressure on the visitors’ line saw Blacker dive over at the posts on the hour mark for a try that was again converted by the full-back.

Despite the desperate attempts of the Dragons to haul their way back into the contest, the Scarlets defence held firm with player of the match Lousi and Dan Davis, Aaron Shingler and Vaea Fifita outstanding. The Scarlets scrum was also proving a big weapon.

With the clock ticking down, the cherry on the cake was provided in the dying seconds when the impressive Davis scooped up a loose ball and it was the flying McNicholl who finished in style in the corner.

Halfpenny converted from the touchline amid rapturous scenes from the home faithful.

Scarlets - tries: S. Evans, D. Blacker, J. McNicholl. Cons: L. Halfpenny (3). Pens: Halfpenny (4)

Dragons - tries: A. O'Brien, L. Jones. Cons: JJ Hanrahan (2). Pen: Hanrahan