His side trailed their Liberty Stadium hosts by 14 points after 20 minutes but sensationally turned things around to snatch a two-point win.
The start may have annoyed Erasmus but the manner of the comeback has helped ease the pain.
“They were going top of the table if we lose the game so the pressure was on from the beginning,” he said at UL yesterday.
“And then the pressure after 15 minutes was even more because they scored two easy tries so, yes, I think it was a satisfying win. The first 15, 20 minutes was terrible from us. Our physicality wasn’t up there so to turn it around was very positive.
"They were totally dominant for the first 15 minutes. For Jacques (Nienaber, skills coach) and for the players to rectify that during the game is very positive.
“They will also learn lessons. You go away from home and respect other teams’ attack. For a team that scored so many tries (this season), you shouldn’t be surprised about the quality of their attack in the first 15 minutes. You should know that and we must learn from that.”
The atmosphere at UL yesterday suggested the manner in which they escaped with a two-point victory after such a dreadful start provided the management and squad with a far greater degree of satisfaction than they derived from easier and more comfortable victories.
If there was a semblance of complacency, it should have been blown away by the shortcomings so evident in that opening spell in Swansea and prepare them for another stiff test against the Scarlets at Thomond Park on Friday night.
“It will be a good test,” acknowledged Erasmus. “Scarlets concede a very low amount of tries. They really defend well.
“They play a more tactical game, although having said that, they vary their game more than the Ospreys.”
Try scorer Jack O’Donoghue picked up an ankle injury and Rory Scannell has a little niggle on the knee but Erasmus isn’t ruling either out of Friday’s contest.
There is disappointment that South African second-row Jean Kleyn is facing a two-month spell on the sidelines because of neck trouble but Erasmus tries to look upon the blow quite philosophically.
“We are disappointed as we would be for any player,” he said. “When we lost Francis Saili, we had to cope. We have lost James Cronin now, he’s been out for five or six weeks. Then there’s Robin Copeland. When you start listing the players that are out, you just sound like you’re making excuses for losing.
“And you know, Jean Kleyn is just like any one of the other players, the next guy will step in and take his opportunity and do well. Any player is a loss for us. So we will miss Jean just like all the others.”
There was irony in Dave Kilcoyne’s omission from the latest Irish squad, given he was Munster’s try-scoring saviour against the Ospreys.
Erasmus said: “I think it is more testament to the quality of players Ireland has available in the loose-head position, but he will get there again, he is good enough to play international rugby.
"He’ll keep on fighting, but we must have quality loose-heads if he doesn’t make it. My thing about ‘Killer’ is, if he’s disappointed or motivated or demotivated, or on a bad week or good week, you always know how he will pitch up for a game: Ready to go. He wants to play well for Munster.”