But things quickly went downhill for the visitors as they lost Barry Murphy to a seventh-minute injury. Murphy's injury jinx against Ulster continued as he sustained a painful looking thumb injury - he broke his ankle in the corresponding fixture at Ravenhill in March 2006.
Late on in the second half, Munster lost Niall Ronan to a suspected dislocated thumb and winger Anthony Horgan was also sidelined through illness.
With replacement winger Keith Earls a late withdrawal due to a stomach bug, the province's video analyst Jason Holland, now aged 35 and playing his first professional game in over three seasons, was pressed into action off the bench.
And with his Heineken Cup heroes still recovering from last Sunday's semi-final win over Saracens and a league game to follow away to Llanelli this coming Saturday, Munster coach Declan Kidney knows the strength of his full squad is truly being tested.
Speaking after the Belfast defeat, Kidney explained: "Niall and Barry took knocks on the thumb and it's not looking good at the moment.
"Keith Earls and Anthony Horgan are not feeling the best. Both of them have stomach bugs. Sometimes you get days like this that roll against you, you know.
"It's a professional game now. We'll work on it, the guys who didn't play (tonight) will train tomorrow morning and we'll see who's best fit on Friday to travel to Wales for the Scarlets game."
On Munster's first loss in their last four meetings with their northern rivals, Kidney felt his side had lacked the necessary cutting edge in attack.
Had they been a little more clinical, Ronan, Horgan and second row Mick O'Driscoll, who lorded it in the lineout, could have picked off a try apiece.
"For long patches we were putting a lot of pressure on Ulster. We just need to take a look at how we finish off some of the scoring chances. The opportunities that came our way, we were not as cohesive as we should have been.
"Obviously there are a few things in attack that we'll take a look at and see how to become a little bit more clinical," added the Munster boss.