Scarlets coach Simon Easterby admitted there were too many errors in his side's game after the region went down 20-13 to defending champions Leinster in the Heineken Cup.
Wing Isa Nacewa scored the visitors' only try with Jonathan Sexton supplying 15 points with the boot.
The Scarlets, who came away with a losing bonus point, scored a try through Gareth Maule and two penalties and a conversion from Rhys Priestland.
Successive defeats have left the Scarlets all but out of Pool Five, with Leinster and Clermont Auvergne now the two favourites to get into the last eight.
Easterby said: "It was difficult to take. Ultimately there was a lot of error count in our game and when you play a team like Leinster you have got to make sure your error count is low and you get a lot right in your game.
"In the first half they won the battle of the breakdown definitely.
"But no excuse – we got what we deserved in the first half.
"I thought at 11-0 down we were starting to chase the game but we had a chat and came back with a couple of scores. We made a few changes."
Northampton captain Dylan Hartley insisted his side were "not out of it" after losing 21-16 against a rampant Castres side in the Heineken Cup on Friday night.
The Saints came into the game on the back of a 24-15 win against Glasgow Warriors at Franklin's Gardens, but knew Castres would prove tough opposition in windy conditions at the Stade Ernest Wallon.
Having only had five days to prepare after the Glasgow game, Northampton were well beaten this evening.
Although the loss disappointed Hartley, the 26-year-old claimed the Aviva Premiership leaders should still be considered as contenders for the trophy.
"We're not out of it," he said. "We've got Ulster next at our place, and we'll know where we are in terms of qualification a lot better after that one. There is still a long way to go in the competition.
"We knew that if we were to be considered contenders for the competition, we need to win games at home against the likes of Ulster and that's where our focus now turns to."
Although the Saints did not do enough for the win, a late rally saw them gain a bonus point. "We said at half-time in the Glasgow game that we would target the bonus point, and it was the same again tonight," Hartley said.
Harlequins director of rugby Conor O'Shea was delighted to come away from the Sportsground with the spoils after a 30-22 win over Connacht.
Ben Botica kicked 20 points on his first Heineken Cup start for Quins, while his half-back partner Danny Care was crowned man-of-the-match after scoring two crucial tries.
Care slipped through in the 31st and 38th minutes to get the English champions back on the rails after they had fallen 19-9 behind.
But despite the best efforts of Connacht's new general Dan Parks, who kicked 17 points, Quins maintained their advantage and denied the hosts a losing bonus point.
Speaking afterwards, O'Shea said: "We are very comfortable to have nine points [after our first two pool matches]. To have denied both Biarritz and Connacht a losing bonus point is a huge thing.
"We have put ourselves in a very good position, but we learned a lesson two weeks ago in Exeter. If we mess around and don't come with our 'game heads' on, any team can do a job and we want to do a job in six or eight weeks' time [against Zebre].
"Connacht will challenge you and at the end of this pool when Biarritz have to come here, this will be one heck of a hard place for Biarritz to come."
Sale head coach Bryan Redpath admitted his team lacked the firepower to compete with the top clubs in Europe after Montpellier fly-half Francois Trinh Duc dismantled his side in a stunning second-half burst.
The France international scored his side's opener on 51 minutes before two clever kicks set up another two tries to send the French side on their way to a 33-18 win.
Until then the Sharks had remained in the contest with Mark Cueto scoring the only try of the first half as they went into the break 12-8 behind.
Redpath was nonetheless pleased with his side's performance against one of the Top 14's pacesetters.
"We played a decent game and the young boys that came here have done exceptionally well in a tough environment," said Redpath.
"Winning here is a difficult challenge and winning matches in Europe is hard.
"We just didn't have enough firepower to compete.
"It got a bit messy and sloppy for us, and we must give credit to Francois Trinh Duc. He set up two great tries with chip kicks and finished one himself.
"We could have crumbled at 12-8 but didn't. We fought back, we had opportunities, but they got a couple of lucky bounces."