ASM Clermont Auvergne remain in the driving seat to qualify from Pool 4, with Harlequins hot on their heels ahead of Saturday afternoon’s mouth-watering match up at the Twickenham Stoop, but Scarlets are mathematically still in with a shout of a place in the last eight.

Young wing Kristian Phillips was their match winner, with his stunning solo score just past the hour handing them a six-point lead that they never relinquished.

Wales fly-half Rhys Priestland picked up the Heineken Man of the Match award with an assured display that ended with a 14-point haul courtesy of four penalties from five attempts and the conversion of Phillips’ try.

British & Irish Lions stars Jonny Sexton and Mike Phillips stood out for Racing, with the scrum-half grabbing his side’s early try, but the Scarlets deservedly stopped a run of six straight defeats.

The Scarlets were ahead as early as four minutes as Priestland made up for an even earlier miss by hitting the target from straight in front of the posts.

But Racing showed their obvious potential when Phillips initiated a charge down the left that only ended when Argentine playmaker Juan Martin Hernandez stepped into touch five metres short and they were in front with just nine minutes gone.

Racing may have only scored 14 tries in 16 domestic games but their intentions were clear when Sexton opted to ignore a simple shot at goal in favour of an attacking lineout. And that enterprise brought an immediate reward when Sexton’s inside ball to Juan Imhoff put Racing on the front foot and Phillips snuck over from close range just after Sexton himself had been hauled down just short.

Sexton added the extras from midway between the left touchline and the posts and Racing were 7-3 up ahead and looking to kick on.

They seemed set to stretch that lead almost immediately as they had the Scarlets in all sorts of trouble but the visitors somehow escaped unscathed following a dogged defensive effort. Virgil Lacombe was denied a try by the efforts of openside John Barclay and two more Scarlets colleagues as they held the hooker up over the line but Racing should still have been celebrating moments later. Having seemingly been on the brink of a penalty try following a brace of quick-fire penalties at the resulting five-metre scrum, Racing were undone as Phil John got underneath former Northampton prop Brian Mujati to win turnover ball and avert the danger.

The rest of the half was much more even, with Priestland cutting the gap to 7-6 with another penalty two minutes before the break and Sexton restoring the four-point gap with the final kick of the half.

Phillips and Sexton combined again to put Benjamin Fall in space down the left seconds after the restart but it was the Scarlets who should have been celebrating the next score through wing Frazier Climo. Priestland’s clever chip ahead left the Racing defence in disarray but Climo couldn’t gather with a clear run to the lien ahead of him.

Priestland did cut the gap with a third penalty before Racing blew a similarly gilt-edged chance after 50 minutes when Sexton’s scoring pass to Fall was picked off by Aled Thomas. The Scarlets almost turned the mistake into a try of their own as they raced fully 70 metres but the bounce of the ball again went against them as Priestland chipped crossfield to Barclay.

Priestland then put the Scarlets in front with a fourth strike after 55 minutes before Juan Martin Hernandez made it 13-12 on the hour as Sexton recovered from a knock.

But Kristian Phillips then left five Racing defenders for dead to claim a quite brilliant try for the Scarlets two minutes later, with the former Ospreys flyer displaying devastating pace in providing the most memorable moment of the match.

With Priestland adding the conversion, the Scarlets were 19-13 ahead and they held on for the final 15 minutes with relative ease.