Leinster and Connacht secured home semi-finals in the Pro12 on Saturday, as Ulster booked their place in the play-offs and both Munster and Zebre earned qualification for next season's European Champions Cup.
Glasgow Warriors headed into the final round of regular-season fixtures as league leaders, but a 14-7 defeat at Connacht, allied with Leinster's 50-19 thrashing of Benetton Treviso, saw the Scottish side slip to third.
Bundee Aki and Tiernan O'Halloran claimed tries for Connacht, who are now set to host Glasgow again in the semi-finals while Ulster travel to Leinster. The latter ran in eight tries against Treviso to snatch top spot, Richardt Strauss responsible for two.
Munster's 31-15 victory over Scarlets assured Anthony Foley's men of sixth spot and a place in Europe's premier club competition in 2016-17.
Scarlets had held hopes of climbing into the top four, but even a victory would ultimately not have been enough for the Welsh region to make the semi-finals as Ulster earned a bonus point in a 46-26 victory over Ospreys at the Liberty Stadium.
Zebre climbed off the foot of the table and claimed Italy's sole berth in the Champions Cup - at Treviso's expense - with a 47-22 thrashing of the Dragons.
Meanwhile, Edinburgh's slim hopes of finishing in the top six ended with a 21-17 home defeat to Cardiff Blues.