A dominant third quarter display saw the Ospreys claim the derby spoils with a 54-36 victory over the Scarlets at the Swansea.com Stadium.

The Scarlets had looked in control 24-14 ahead at half-time, but the match was flipped on its head after the break with the hosts running in 33 unanswered points.

Two late tries from Kieran Hardy and Ryan Conbeer - who claimed a personal hat-trick - at least salvaged a try bonus point for the West Walians, which could still prove important as the battle for the Welsh Shield and Champions Cup qualification goes down to the wire.

Scarlets, playing their first game at the ground since 2019, almost made the perfect start with Costelow hitting a Gareth Davies flat pass, but his run was halted by Keelan Giles in the corner.

Nevertheless, the Scarlets’ bright opening was rewarded with a sixth-minute penalty from the fly-half after his half-back partner Davies had sliced open the home defence.

Ospreys hit back strongly and on 15 minutes, replacement prop Nicky Smith powered over from close range.

However, back came the Scarlets and it was that man Costelow who provided the trigger for a Gareth Davies try, with flanker Tomas Lezana providing the link and scoring pass. Costelow added the extras.

Sosban Fach was ringing around the ground again five minutes later when slick hands found Conbeer out wide. The speedster still had plenty to do, but rounded his man to finish brilliantly wide out. Costelow nailed the touchline conversion.

The see-sawing nature of the contest continued when an Alex Cuthbert break paved the way for No. 8 Morgan Morris to plough over at the posts for the Ospreys second, but the Scarlets weren’t finished and after opting for a five-metre scrum instead of three easy points, their ambition was rewarded with a second try for Conbeer, thanks to a lovely looped pass from Costelow.

A breathless first half ended with a superb Johnny Williams turnover to ensure the visitors led 24-14 at the break.

It was the Ospreys who struck first in the second period with a break from Anscombe leading to a try from wing Giles and that led to a dominant third period in which the game was turned on its head.

After a breakaway from the home side, wing Corey Baldwin was yellow carded for a deliberate knock-on and in a matter of minutes, player of the match Dewi Lake powered over for two short-range tries.

Centres Michael Collins and Owen Watkin added further scores as the Ospreys took the game out of sight, but the Scarlets did salvage a try bonus when replacement scrum-half Kieran Hardy darted away for a superb solo score then Conbeer completed his hat-trick for try number five.

The final word, though, went to the Ospreys, who completed the scoring through replacement hooker Sam Parry.

The defeat leaves the Scarlets’ URC play-off hopes over, but they remain five points clear of the Ospreys in the battle for the Welsh Shield with the Ospreys having a game in hand - against the Dragons next weekend.