Munster travelled to Wales sitting pretty in third in the RaboDirect PRO12 table but faced a resurgent Dragons side who outplayed the visitors for 65 minutes.
A yellow card for Munster's Tomas O'Leary in the 58th minute swung the advantage very much in favour of the home side but by the time Munster returned to 15 men they had weathered the storm and full-back Felix Jones delivered a knock-out blow five minutes from time with an interception try.
Fly-half Ian Keatley got the champions off to a solid start when he chipped over a penalty in the third minute - his pack coming out on the right side off Italian referee Carlo Damasco at the first scrum.
The Dragons roared back through a typically robust run by centre Andy Tuilagi. From the ruck scrum-half Wayne Evans brought his forwards into the game well, particularly lock Luke Charteris who was making his first start of the season.
The attack was a warning of what was to come for Munster. First fly-half Lewis Robling drew the hosts level in the 18th minute then full-back Will Harries found some space on the left wing and hared down the touchline.
Cutting in, he avoided opposite number Jones and led the cover tacklers a dance before handing the ball on to the grateful Ashley Smith and the centre stepped off his right foot to score the opening try.
Robling missed a straight-forward conversion and it didn't take long for Keatley to peg the hosts back with two well-taken penalties.
The rookie fly-half made amends for his earlier imprecision to the put hosts back in charge with a penalty on 29 minutes and the scores remained at 11-9 to the hosts until half-time
Tuilagi was forced off six minutes into the second half and without their battering ram the Dragons opened up to play some wonderful team rugby, with the forwards particularly to the fore.
It had Munster searching for answers but with none coming they launched into the break-down to try and slow the home side.
On 58 minutes referee Damasco had seen enough and sent scrum-half O'Leary to the sin bin for repeated infringements and the Dragons tried to turn the screw.
But their only yield was through Robling's third penalty of the night in the 65th minute.
Munster's riposte was immediate and determined. Still down to 14 men they resolved to put right wing Luke O'Dea into the corner to draw things level at 14-14.
Four minutes later the champions were ahead after Dragons' blindside Jevon Groves tackled Lifeimi Mafi around the collar and replacement Scott Deasy slotted the penalty.
Then came Jones who gulped up a loose pass by Lewis Evans to go in between the sticks from 50 metres out. Deasy converted meaning Munster still haven't lost in 2012.
|Newport Gwent Dragons Score Card|
|Munster Rugby Score Card|