Leinster moved closer to the league title after securing their most important win of the season, 21-12 over Munster at the RDS.
Felipe Contepomi kicked Munster out of the title race as he landed six penalty goals from eight attempts in this niggly inter-provincial clash.
Jonathan Sexton topped off the win on Saturday with a late drop goal as the league leaders put 12 points between them and the second-placed Cardiff Blues.
Worryingly for Munster, with their Heineken Cup semi-final trip to Saracens just a fortnight away, half-backs Ronan O'Gara and Peter Stringer both picked up injuries.
O'Gara did not return for the second half after injuring himself at a ruck, while Stringer had to be stretchered off in a neck brace after his team-mate Anthony Foley accidentally caught him with an elbow.
England Under-20s head coach Martin Haag was full of praise for his World Rugby Under-20 Championship-winning side after Harry Mallinder inspired them to a 45-21 win over their Irish counterparts and a third title in four years.