Racing 92 cut loose in the last 30 minutes to turn a nervy encounter with Scarlets into a noisy Parisian party and clinch top spot in Pool 4 and a home quarter-final in the European Champions Cup with a 46-33 victory on Saturday.
The hosts had not lost a home European game since moving into their La Defense Arena in October 2017 and were already sure of a place in the last eight.
However, they trailed the Welsh team after 50 minutes.
Winger Juan Imhoff and centre Henry Chavancy touched down in the first half but a try by Steff Evans and the kicking of Dan Jones meant the Scarlets ended the half one point ahead.
The points continued to flow at the start of the second half. Evans kicked behind the home defence and Johnny McNicholl raced through to score after 45 minutes.
But two tries from Ireland wing Simon Zebo bracketing touchdowns by Virimi Vakatawa and Teddy Iribaren put Racing in control.
Scarlets kept fighting and were rewarded with McNicholl’s late second try.
In the other game in the pool, Ulster awoke in the last 21 minutes as prop Marty Moore and winger Robert Baloucoune scored tries to overturn a 13 point deficit in Leicester.
Racing had already qualified on Friday when Edinburgh beat Montpellier 19-10, a result which also put the second Scottish side, Glasgow Warriors into the last eight.
In Saturday afternoon’s early games, Saracens saw off a furious challenge from the Warriors to win 38-19 at Allianz Park and clinch first place in Pool 3 and the top seed in the quarter-finals.
© Agence France-Presse (Additional Edits By Oisin McQueirns)