Holders Saracens are a win away from the Champions Cup final after beating Leinster, while Racing 92 powered past Clermont Auvergne.
Leinster cruised to a record seventh Pro14 title as they defeated fellow Irish side Ulster 27-5 in Dublin in Saturday's final.
There will be an all-Irish final in Pro14 after Ulster came from behind to defeat Edinburgh and book a date with Leinster.
The Scarlets can still quality for the Pro14 play-offs next week after beating the Dragons, but they need Connacht to do them a favour.
Leinster picked up where they left off in the Pro14 as they held off Munster in a thrilling contest in Dublin on Saturday.
Ahead of their relegation to the Championship, Saracens have been told they can continue to play in this season's European Champions Cup.
Fergus McFadden played in a World Cup and six Six Nations campaigns, twice conquering Europe with Leinster, but the time has come to retire.
Ryan Baird and Dave Kearney both scored hat-tricks as Conference A leaders Leinster routed Glasgow Warriors on Friday.
Cian Healy will miss the remainder of the Six Nations after the prop was injured during Ireland's loss to England.
Leinster became the first Pro14 side to win their first 12 league matches of a season after they overcame Ospreys on Friday.
The Ospreys claimed only their second Pro14 win over the season at the expense of high-flying Ulster in a stormy Swansea.
Ireland's James Ryan is hungry for more honours with club and country after signing a new deal.
Ahead of crunch Six Nations matches with Wales and England, Ireland were dealt a blow with Garry Ringrose ruled out.
Johnny Sexton and Jordan Larmour have been joined by uncapped number eight Caelan Doris in Ireland's team to face Scotland.
Johnny Sexton expects to lead Ireland against Scotland in Dublin and Jordan Larmour is expected to be in contention.
At the end of another week of crisis, Saracens had rare cause for cheer as they reached the quarter-finals of the European Champions Cup.