A new-look back-three of Ariel Robles, Jimmy Hawkshaw and Rob McGrath did a good deal of damage as title holders Clontarf brushed Young Munster aside at Castle Avenue.
A shock result had been on the cards when Young Munster led 14-3 approaching half-time, with returning centre Shane O'Leary standing out for the visitors.
The Connacht prospect scored a 25th minute try, shrugging off two defenders on the way, and kicked two penalties, with Ben Martin also landing a monster kick from halfway.
Despite having full-back Derry O'Connor sin-binned, the Cookies were taking the game to last season's league winners.
David Joyce notched 'Tarf's lone score from a penalty and it looked like Munsters, aided by a strong set piece game, would stay more than a converted try ahead for the break.
However, the north Dubliners bounced back in timely fashion as winger Jimmy Hawkshaw finished off a 34th minute try – a score that Young Munster head coach John Staunton felt should not have been awarded as he felt Hawkshaw put his foot in touch before dotting down.
It was a big setback for the Cookies as Joyce's subsequent conversion and a further penalty before the half-time whistle reduced the arrears to just a single point.
Clontarf boss Andy Wood admitted afterwards that it was 'a very touch examination' for his charges during the first 40 minutes, but they gained momentum during a crucial period in the third quarter.
Staunton lamented the injury-enforced withdrawal of influential tighthead Evan Ryan in the 45th minute and just two minutes later Clontarf scrum half Peter du Toit (pictured below) touched down after charging down a kick from his opposite number Evan Mulcahy.
The hosts' pacy back-line was suddenly causing problems for Munsters and number 8 Martin Garvey did well to finish off a third try under pressure from three covering defenders.
'Tarf secured the bonus point in the 63rd minute when Rob McGrath crowned his top flight debut with a try, as the sin-binned Sean Rennison watched on from the touchline.
Again, Young Munster's luck evaded them as a charged down kick led to full-back Ariel Robles sparking a length-of-the-pitch counter, combining with Hawkshaw and replacement Sam Cronin to send McGrath in by the posts.
Munsters were not finished though and after 'Tarf had Conor O'Keeffe and Karl Moran sin-binned, replacement Barry Gibbons touched down to make it 30-19.
But David Hegarty's superbly timed pass put fellow replacement front rower Brian Keelan over for a fifth and final try which confirmed 'Tarf's winning start.
Referee: Leo Colgan (IRFU)