Scarlets became the first Welsh team since 2012 to reach the knockout stage of the European Champions Cup when they clung on to a 30-27 home victory over Toulon on Saturday.
In the other game in Pool 5, Bath won 47-28 in Treviso, but despite the bonus point, finished behind Toulon who also qualified for the last eight as one of the best runners-up.
Earlier, in Pool 2, last year's losing finalists Clermont had secured a home quarter-final when they beat Scarlets' fellow Welsh team Ospreys 24-7, while holders Saracens crushed Northampton 62-14 to take second spot and keep their hopes of progressing alive.
In the first half at Llanelli, Scarlets, who started the day a point behind Toulon, again produced scintillating attacking rugby but the French team responded.
Winger Tom Prydie put the home side ahead after three minutes, only for Duane Vermeulen to reply just two minutes later with a try following a lineout.
Former England winger Chris Ashton intercepted a Scarlets pass near his own line and raced down the field to put Toulon ahead, but home centre Hadleigh Parkes replied after Toulon failed to clear the subsequent kick-off.
Fly-half Dan Jones dived over following a lineout and Scarlets led by six at the end of a breathless half.
In contrast, the second period yielded just three penalties, the last of them in the 57th minute.
That led to a nerve-jangling final quarter, but the three-point margin suited both teams.
Scarlets won the group while Toulon collected a losing bonus point to edge Bath and climb to 19 points, enough to reach the quarter-finals.
- Clermont top tough pool -
In Clermont, Nick Abendanon slid on to Morgan Parra's chip after 25 minutes for Clermont's first try, before two Parra penalties stretched the hosts' lead to 13-0 at half-time.
Ospreys made the home team sweat as Ashley Beck's try, converted by Dan Biggar, cut the deficit to six points with 10 minutes left.
Clermont wrapped up a fifth win of the pool stage as Parra and Greig Laidlaw kicked late penalties and Luke McAlister touched down their second try.
The reigning French champions have struggled domestically and sit 10th in the Top 14 table, but have impressed in the Champions Cup as they bid for a first European Cup crown after losing three finals in five years.
"Morgan Parra played just like he has done this season, with a lot of control," said Clermont sporting director Franck Azema, who was unhappy when his team failed to secure qualification with defeat at Northampton last weekend.
"That's what I was expecting from my players after the Northampton match."
Saracens, who are chasing a third straight Champions Cup title, would have been eliminated by an Ospreys win.
Instead they cruised to a bonus-point victory over English rivals Northampton to improve their chances of taking one of the three last-eight places for the best second-placed teams.
Saracens secured a bonus point inside 35 minutes and finished with seven tries.
Montpellier and English champions Exeter were both eliminated with defeats in Pool 3.
Montpellier lost 23-14 at home to already-qualified Leinster, while Exeter fell 28-21 away to Glasgow.
Exeter coach Rob Baxter accused his side of being "soft", saying: "Did we really stand in front of them like a brick wall?
"We got picked off by length-of-the-field tries and if you give up length-of-the-field tries you are not going to win many games."