Scarlets heaped more misery on closest rivals Ospreys with a record-breaking bonus-point derby win in Llanelli.

Wings Ryan Conbeer and Steff Evans scored two tries apiece, with Kieran Hardy and Josh Macleod also crossing as Scarlets ran in six tries.

This was was supplemented by 12 points from the boot of Leigh Halfpenny as Scarlets moved second in Conference B.

Ospreys are in disarray with a 12th defeat in 13 matches this season and could not even muster a point.

This hammering was a new low for Ospreys against Scarlets in a wretched campaign - eclipsing the 40-17 defeat in 2017 - despite the valiant efforts of captain Justin Tipuric who is out of contract at the end of the season.

Ospreys have dropped to bottom of Conference A following a 10th consecutive loss with their solitary win of the season coming in a 24-20 success over Benetton on 12 October.

With head coach Allen Clarke no longer in charge of first-team affairs the day-to-day ship is being steered by Carl Hogg and Matt Sherratt.

Consultant Mike Ruddock is coming to the end of an initial one-month appointment after looking at the region's coaching set-up. Whether that is extended remains to be seen.

In contrast, Scarlets looked assured with the back-row of Aaron Shingler, Macleod and Blade Thomson excelling in the Llanelli rain and fly-half and man-of-the-match Angus O'Brien having a hand in most of Scarlets' tries.

Scarlets had a busy Christmas off the field, with the official news emerging that head coach Brad Mooar will join the New Zealand backroom staff at the end of the season.

There as also confirmation British and Irish Lions full-back Liam Williams - who was present at the match - will rejoin the region from Saracens for next season.

Scarlets had made three changes to the team that lost to Dragons, with O'Brien and Conbeer replacing the injured Dan Jones and Johnny McNicholl. Scotland back-rower Thomson also started ahead of Uzair Cassiem.

Ospreys made two changes but were still without Wales internationals Alun Wyn Jones and George North, who were part of a casualty list that included 16 players.

Back-rower Morgan Morris replaced Dan Lydiate, while Lesley Klim was a late withdrawal with Tom Williams coming on the wing.

Ospreys were further hampered when centre Kieran Williams also pulled out late, with teenager Tiaan Thomas-Wheeler drafted in.

The Ospreys midfield disruptions continued early on when former Scarlets centre Scott Williams was forced off with a a facial injury and never returned.

James Hook, who had not been named in the original match-day 23, was his permanent replacement.

Scarlets early pressure told when Halfpenny slotted over the opening penalty before the quality shone through, with an inside pass releasing Aaron Shingler and Steff Evans finishing the move. Halfpenny converted.

O'Brien again was the creator with his pinpoint kick expertly taken by Conbeer who sprinted away to score. Halfpenny converted to give the hosts a deserved 20-0 interval lead.

Ospreys' woes continued in the second half when Luke Morgan was yellow-carded for a high tackle on Conbeer.

Scarlets made the extra man tell when Conbeer glided over for a second try where Morgan would have been positioned.

This try followed clever distribution work from O'Brien, who also produced a brilliant left-foot kick to set up Evans for his second score.

Scarlets showed no mercy with replacement scrum-half Hardy and flanker Josh Macleod scoring tries and Hardy even having one disallowed for a late tackle from Jake Ball on Luke Price.

Scarlets duo Ball and Werner Kruger were yellow-carded for late professional fouls as Ospreys sought a consolation score but failed.

Scarlets head coach Brad Mooar

"I am over the moon and it was outstanding. We knew we had left ourselves down against Dragons and we were better than that.

"It was the perfect week and we could not wait to get out on the park. It was just wonderful to see them go out there and express themselves.

"To have the enjoyment of 13,600 fans here backing us was excellent and we were thrilled to represent them."

Ospreys forwards coach Carl Hogg:

"Clearly it is disappointing and we got beaten in almost every fact of the game, starting with energy and enthusiasm.

"We have had some hard Champions Cup games and put in a lot of emotional energy last Saturday against Cardiff Blues with no tangible rewards.

"We are in a difficult time with players being away at the World Cup and a lengthy injury list. The only people who can solve it in the dressing room is us and that's what we intend to do."

Scarlets: Halfpenny; Conbeer, Hughes, Parkes, Evans; O'Brien, Davies; Jones, Owens (capt), Lee, Ball, Lousi, Shingler, Macleod, Thomson.

Replacements: Elias, Price, Kruger, Ratuva, Cassiem, Hardy, Lamb, Asquith.

Ospreys: C Evans; T Williams, Thomas-Wheeler, S Williams, Morgan; McKenzie, A Davies; Smith, Otten, Fia, Beard, B Davies, Cracknell, Tipuric (capt), Morris .

Replacements: Lake, Fawcett, Gardiner, Orie, Lydiate, Venter, Price, Hook.

Referee: Craig Evans (WAL)

Assistants: Dan Jones (WAL) and Wayne Davies (WAL)

TMO: Jon Mason (WAL)