Play-off chasing Ulster punished Scarlets ill-discipline to claim a 31-20 victory on a sun-kissed afternoon at Parc y Scarlets.

Scarlets led 6-3 at half-time, but having been reduced to 13 men with the sin-binnings of Taine Plumtree and Gareth Davies, Ulster turned the game on its head with three quickfire tries in the space of 14 minutes.

Again, there were plenty of positives for a Scarlets side that started with 15 Welsh players, but Dwayne Peel’s men will rue that period after half-time.

In glorious sunshine, it was the home side who started this BKT United Rugby Championship round 16 contest the stronger and were rewarded with a 12th-minute penalty from fly-half Sam Costelow.

With Scarlets enjoying the better of early territory and possession the Wales international doubled the advantage on 26 minutes only for scrum-half John Cooney to respond for Ulter with a three-pointer of his own.

A scything break from inside his own 22 from Gareth Davies and breaks from Ioan Nicholas and Taine Plumtree were the home side’s best moments with ball in hand, but the second quarter saw the Scarlets largely in defensive mode.

Ulster were twiced held up over the line as the Irish province dominated the final exchanges of the half and it led to Scarlets being reduced to 13 men as Plumtree (cynical infringement) and Davies (trip) were shown yellow by Italian referee Gianluca Gnecchi.

With three minutes of first-half stoppage time on the clock, Ulster once again thought they had scored through their forwards, but once again the Scarlets defence managed to hold them out.

However within 10 minutes of the restart, Ulster had take a firm grip of the contest.

Two minutes after the restart, a home line-out went astray and centre Stuart McCloskey made the most of acres of space to race in under the posts. No. 8 Nick Timoney then charged over from an attacking scrum. Both tries were converted by Cooney to push Ulster into a 17-6 lead.

Ulster had their third when flanker David McCann plunged over from close range leaving the home side with a mountain to climb.

The Scarlets did get a score back, thanks to the power of No, 8 Carwyn Tuipulotu from close range - a score converted by Costelow.

But the home side were unable to secure the kick-off, Ulster set up camp in the home 22 and Ireland wing Jacob Stockdale was put away wide out.

The Scarlets refused to throw in the towel and crossed for a superbly-crafted second try on 67 minutes.

Replacement Ioan Lloyd was the architect, slicing through before feeding Tomi Lewis for the score.

Costelow converted, but despite a couple of late opportunities to get into range of the visitors, the Scarlets couldn’t take their chances.

Home favourite Scott Williams entered the fray for his final appearance at Parc y Scarlets, replacing the injured Tuipulotu as Scarlets searched for some late consolation.

But Ulster saw out the win to keep their play-off hopes firmly alive.

After the match, presentations were made to the departing players, including club greats Ken Owens, Jonathan Davies and Williams, with the fans with them on the pitch to show their appreciation.

Scarlets - tries: C. Tuipulotu, T. Lewis. Cons: S. Costelow (2). Pens: Costelow (2),

Ulster - tries: S. McCloskey, N. Timoney, D. McCann, J. Stockdale. Cons: J. Cooney (4), Pen: Cooney.

Attendance: 6,881