Denis Leamy (right) scored two Munster tries in the first half
Munster (20) 32
Tries: Leamy (2), Murphy, Quinlan.
Cons: O'Gara (3)
Pens: O'Gara (2)
Cardiff Blues (13) 18
Try: Robinson, Lewis
Pens: Blair (2)
Munster kept their 100% record in this year's Heineken Cup by holding off gritty Cardiff Blues in Limerick.
Two Denis Leamy tries helped Munster lead 14-3 after 19 minutes but Jamie Robinson's breakaway try cut the Irish side's lead to 20-13 at the interval.
Barry Murphy's try extended Munster's advantage but Mark Lewis replied with a Cardiff touchdown and Robinson then should have notched another Blues try.
Munster regained control and Alan Quinlan's try ensured the bonus point.
Blair's early penalty put Cardiff ahead but Munster responded emphatically with Leamy barging his way past a weak Nick MacLeod tackle to score the game's opening try in the seventh minute.
Munster had already showed their intent by turning down a couple of straightforward penalty chances, instead opting to turn the screw on the Cardiff defence.
Blair missed a great chance to cut Munster's lead to a point in the 18th minute and things got worse for Cardiff when Peter Stringer's quick thinking set up Leamy's second try moments later.
Seeing Leamy pleading for the ball, Stringer took a line-out throw on the edge of the Blues 22 and the number eight charged over for an opportunistic try.
Blair and O'Gara then swapped penalties to leave Munster in firm control at 17-6 ahead.
However, completely against the run of play, Cardiff got back into the game when Barry Murphy's wayward midfield pass enabled Jamie Robinson to claim a breakaway try just before half-time.
Blair's conversion cut Munster's lead to 17-13 but O'Gara had time to add another penalty in first-half injury-time after Martyn Williams had been sin-binned for killing the ball in a ruck.
Murphy atoned for his mistake by scoring Munster's third try on 48 minutes after Stringer had disrupted the Cardiff scrum in the Welsh team's 22.
However, Cardiff's superb defence kept them in the contest and they showed attacking potency of their own when Martyn Williams' looping pass set up a try for replacement Mark Lewis which cut Munster's lead to 25-18.
After Blair had missed the conversion, Jamie Robinson squandered a glorious chance to put Munster under real pressure by knocking on in midfield when a third Cardiff try looked certain following a superb Martyn Williams break.
Munster played the final 10 minutes in Cardiff territory but the bonus-point try wasn't secured until the final play of the game when a 10-man drive saw Quinlan barging his way over the line.
Munster's Denis Leamy:
"If we had been told before the back-to-back games against Cardiff that we would get nine points from the two matches, we would have taken it.
"All credit to them. They made it extremely difficult for us and they stood up and fought very hard."
Munster coach Declan Kidney:
"Certainly we have to improve a lot but I'm delighted that we won and gained a bonus point.
"I believe we may have to win our two remaining games (away to Bourgoin and at home to Leicester) to top the pool."
Blues coach Dai Young:
""We're hugely disappointed with the final score. We played with courage and that last Munster try was a bit of a kick in the pants.
"We had a lot of field possession and gave it away. But I have to say we were given no chance coming here to Thomond Park and we did well in the circumstances and really gave Munster a game.
"They have four wins now and are right on course to make the quarter-finals. It is a credit to them that they won it last year and are showing the same fight this season."
Munster: S Payne; J Kelly, B Murphy, T Halstead, I Dowling; R O'Gara, P Stringer; D Hurley, F Sheahan, J Hayes, D O'Callaghan, P O'Connell (capt), A Quinlan, D Wallace, D Leamy.
Replacements: Pucciariello for D. Hurley (64).
Not Used: Kyriacou, Wyatt, O'Sullivan, O'Leary, Manning, Mafi.
Blues: B Blair; T James, J Robinson, T Shanklin, C Czekaj; N Macleod, M Phillips; J Yapp, T Rhys Thomas, T Filise, B Davies, D Jones, S Morgan, M Williams, X Rush (capt).
Replacements: Stcherbina for James (34), G Williams for Thomas (58), G. Powell for Filise (51), Lewis for Jones (52), N Robinson for Stcherbina (57).
Not Used: White, Evans.
Sin Bin: M. Williams (40).
Referee: Joel Jutge (France).