Munster halted their five-game losing run and completed the double over Ulster this season by beating their interprovincial rivals 9-7 on Saturday to stay in touch with the leading sides in the Guinness PRO12.
Munster fell to their fifth straight defeat in all competitions as Zane Kirchner's last-minute intercept try sealed a 24-7 win for Leinster at Thomond Park.
After just two rounds of European rugby this season, including some teams having only played a solitary game, the prognosis is already dire for the Guinness PRO12 sides.
Simon Zebo scored a late try to secure a bonus point for Munster as they beat Benetton Treviso 32-7 at Thomond Park in their opening European Rugby Champions Cup game.
Replacement CJ Stander was the hero as Munster stole a 20-18 Guinness PRO12 victory in the final minute to leave Ospreys winless from their opening two matches.
Conor Murray ran in a hat-trick of tries as Munster hammered the Newport Gwent Dragons 50-27 at Irish Independent Park to book a home Guinness PRO12 play-off.