Gavin Coombes scored two tries as Munster recorded a 17-6 away victory that left Northampton’s European hopes hanging by a thread.
Following a 46-12 thrashing at La Rochelle last weekend, Saints needed a response but despite a spirited performance they were taught a lesson in wet-weather rugby by the two-time European champions.
The defeat leaves Saints with no points from their opening two fixtures and with the reverse fixture in Limerick and a home game against reigning champions La Rochelle to come, their chances of qualifying for the knockout rounds look bleak.
In contrast, Munster look set to qualify with the four points picked up here adding to the losing bonus point obtained in their opening day 18-13 defeat at the hands of Toulouse.
Joey Carbery converted both of the tries scored by Coombes and added a penalty, with Fin Smith kicking two penalties for Northampton.
Courtney Lawes was a late withdrawal for Saints with a glute-muscle problem and they suffered another setback when Munster opened the scoring.
The visitors had the better of the opening exchanges and were rewarded when Coombes finished off a succession of forward drives.
Carbery converted before Smith put Northampton on the scoreboard with a simple penalty to leave them trailing 7-3 at the end of a competitive first quarter.
The playing conditions worsened with steady rain falling and the hosts made a number of handling errors. Their opponents were also winning the battle at the breakdown where Saints gave away a number of penalties for not releasing.
Carbery kicked one of these to extend the lead but this was soon nullified by a second success from Smith.
Just before the interval, Munster scored a crucial second try when Coombes careered away from a line-out to crash over with Carbery’s conversion giving his side a deserved 17-6 half-time lead.
After the interval the miserable conditions continued to frustrate Saints’ efforts to play an expansive game, with the Munster half-backs enjoying the better of the kicking game.
The third quarter was meandering along in a featureless fashion until the feisty game erupted in the 53rd minute with a mass brawl involving most of the players and after TMO reviews flankers Jack O’Donoghue and Lewis Ludlam were both yellow-carded.
Four minutes later, the Irish were dealt a further blow when their replacement Craig Casey was sin-binned for taking out James Ramm in the air.
Northampton had to make their numerical advantage count but Munster’s defence was relentless and Casey was able to return with no damage done to the scoreboard.
However Carbery became the third Munster player to be sin-binned in 16 minutes as Saints continued their assault on the opposition line, but all their efforts were in vain as the second half finished scoreless.
