Having opened their account with a good home win over Castres Olympique, Matthew Rees brought his side into England to try to find an antidote to the power of the Saints’ scrum and driving line-out.

They must have done their homework because from the first scrum they fashioned a blindside try for full back Liam Williams and never looked back from there. Welsh World Cup hero Rhys Priestland added the conversion and the Scarlets were on their way to a famous win.

The Saints hadn’t been beaten in a European game since Biarritz Olympique went away with the spoils way back in 2007 and, of course, had gone eight games unbeaten on their way to their second final last season.

But their defeat at the hands of Leinster in Cardiff last May was the start of a run of what are now three consecutive defeats. If the loss in Limerick in Round 1 was a bitter pill to swallow, as Ronan O’Gara landed his last gasp drop goal, home director of rugby Jim Mallinder had no qualms about this second Pool defeat.

“We have to look at ourselves and we were very disappointing in many areas. We played badly and deserved to come second,” admitted Mallinder.

“They put us under a lot of pressure at the breakdown and we didn’t look after the ball well enough. Our performance wasn’t good enough.

“This was always going to be a tight Pool, but to lose our first two games is a massive blow to our chances of qualifying for the quarter-finals this year.”

The Saints’ scrum grew in confidence, and power, as the first-half wore on, but the Scarlets dominated possession and looked the most dangerous of the two sides and likely to score.

Ryan Lamb landed a penalty after 18 minutes, but there was drama from the restart. Priestland kicked high and deep into the home 22 and Scottish wing Sean Lamont chased and jumped to tap down ahead of Courtney Lawes.

TV replays later showed that Lamont may have been in front of the kicker at the drop out, and both Chris Ashton and Lee Dickson thought the ball had gone forward from Lamont’s leap, but play was allowed to go on and Aaron Shingler picked up and outpaced Ashton to score in the left corner.

Priestland’s inch perfect, touchline conversion merely added insult to injury and there was worse to come before the half-time whistle. Two more Lamb penalties cut the deficit to five points and now more pressure was coming from the home side.

But a sky high bomb from Priestland was dropped by Samoan international George Pisi, who was drafted in at short notice to replace the injured Ben Foden, and George North and Jonathan Davies snapped up the loose ball to create a try for replacement back row man Matt Gilbert.

The conversion was no problem for Priestland and the Scarlets were flying at 21-9 at the break. It didn’t help the home cause that Lamb missed a penalty shot from half-way on the stroke of half-time and it got worse when the outside half hit an upright from close range.

Even though the Saints regathered possession, there was yet another handling mishap on the Scarlets 22 as Chris Ashton dropped a vital pass. Priestland fly-hacked it downfield with his left foot, George North hared after it and beat Lamb to a second touch on the home 22 and Priestland won the race for the bonus point try.

The outside half added a fourth conversion and the Scarlets were in total control at 28-9. But there was a sting in the tail as Pisi made amends for his earlier defensive lapse with a try and then England flanker Tom Wood emerged from a driving maul to race clear from 40 metres.

Both tries were converted by Lamb, the latter cutting the gap to a mere five points. The clock showed 15 seconds left to play, but the referee allowed play to go on. It meant saints found themselves with one last play to try to do a Munster and win the game in the time red zone.

A knock on just outside their 22 ended their faint hopes and the Scarlets moved on to nine points to top Pool 1.