Even though it was a friendly match, there was still plenty of crunching tackles and confrontation from both sets of players to keep the tension high.
Valenese Malifa kicked the home side in front with a penalty inside the opening few minutes and the fly-half then fed winger Justin Boyd to crash over in the corner for the first try of the game.
The tricky number ten added the conversion and that gave Munster a big wake-up. With a number of familiar names missing for the Irish province, it was left to Paul Warwick to drag them back into the match.
The former Connacht man kicked over a penalty on 17 minutes before assisting tries for Mafi and Holland, as well as proving to be accurate with both conversion attempts.
Scott Johnson's troops were not going to hand over an easy victory though and Boyd sparked a comeback with a chip n' chase that led to the ball being turned over and Louis Stanfill collected to go under the posts.
At half-time, the visitors led 20-15 but it was a totally different game after the interval. It became very scrappy and physical as The Eagles tried to halt the Munster pack from surging forward.
On 49 minutes, a driving maul from the away team produced another try and Jeremy Manning, on for Warwick, got the conversion to further extend their lead.
The same tactic was successful again on 61 minutes when a maul simply barged through the American defence and allowed Sheahan to tumble over the whitewash for a try.
Malifa, who was the star player for the team wearing white, then took advantage of some poor handling in the Munster backline to go over for a try of his own. However, his landing was not straightforward and he had to retire from the game.
The absence of their main points scorer signalled the end for USA as they struggled to deal with the pace of replacements Murphy and Ian Dowling.
There were three disallowed tries, one sin binning, and plenty of incidents that could have ignited a different type of game, but Munster will be glad to come out of this tough work-out with a morale-boosting win.