Leinster now have to win their final two matches, secure two bonus points and hope other results go their way if they are to make the quarter-finals.
Edinburgh thumped a poor Llanelli outfit 38-14, while Ulster ended Munster’s unbeaten run with a 26-17 victory at Ravenhill.
Scrum-half Neil Doak, an Ireland cricket international, scored all of Ulster’s points to add some spice to the Pool A table.
Neath all but confirmed a quarter-final berth with a comfortable 34-7 win over Ebbw Vale, thanks to a hat-trick of tries to fullback Gareth Morris.
Vale flanker Tyrone Morris must have broken a record when he was sin-binned 30 seconds after coming on as a replacement, in his first appearance since being red-carded against Caerphilly a fortnight ago.