Leinster were unable to seal a home semi-final as Benetton Treviso consigned them to a shock home defeat in the Pro14.
Scarlets picked up an impressive win over Glasgow Warriors to keep the pressure on Leinster, while Benetton, Cheetahs and Munster also won.
Leinster suffered a surprise Pro14 defeat against Ospreys on Saturday, while Cardiff Blues won for a fifth game in a row.
Edinburgh and Cardiff Blues both claimed wins to boost their respective playoff hopes in the Pro14 on Friday.
Leinster's big win on Saturday did not quell Scarlets as they kept pace in the Pro14, while Benetton Treviso's promising form was ended.