Ronan O'Gara has admitted Munster have "no margin for error from here on" after they were beaten 27-13 by Sale in Friday's opening Heineken Cup Pool 1 tie.
The Sharks recovered from being 13-9 early in the second half to record a vital win at Edgeley Park. Scrum half Sililo Martens and captain and full-back Jason Robinson both scored tries, with the latter's a 70-yard breakaway effort.
Sitting bottom of the pool, Munster will have to rouse themselves immediately for next Saturday's visit of a power-packed Castres side to Thomond Park if they are to stand any chance of making the Heineken Cup's knockout stages for an eighth consecutive season.
O'Gara, who converted Frankie Sheahan's try and kicked two penalties, cursed the 77th-minute turnover which saw Sebastien Chabal put in a thumping tackle on Munster replacement prop Federico Pucciriello and Charlie Hodgson kick clear, allowing Robinson jet in for his try.
O'Gara said afterwards: "It (The try) was gift-wrapped. If we'd managed to get the ball wide we were looking good, but these are the fine lines you're talking about.
"In fairness to Robinson he got ahead of three or four fellas and showed good control at the finish to score.
"It means we've got to make it up now somewhere else, but there were plenty of positives. If we can work on our phase game under pressure a bit more, I'm confident about our changes. But there's no margin for error from here on."
Munster coach Declan Kidney reckoned that Marten's try, just on the hour mark and with hooker Sheahan in the sin-bin, was the turning point.
"We got into their half possibly only once in the half and finished 10-9 in front, which wasn't a bad return considering how much pressure we absorbed," said the Corkman.
"We knew we needed to be strong in that first ten minutes of the second half, but then they got that score (from Martens) to put them in front.
"We managed to break into their half but then they capitalised (with Jason Robinson's breakaway try) and that was always going to be important on a night like tonight."