Peter O’Mahony conceded a penalty late in the first 40 and Owen Farrell made him pay for his indiscipline to take a 12-9 lead into the half-time sheds.
Immediately after the break Saracens upped the intensity and held on to the ball for well over 20, lung busting phases until flanker Michael Rhodes found a rare gap in the red brick wall to score the first try of the match on 43 minutes.
Farrell added the conversion and two more penalties on 47 and 53 and minutes and Saracens had scored 16 unanswered points in 13 minutes to take control of this game 25-9.
“I though we played really well in the first half but the score was 12-9,” said Sarracens director of rugby Mark McColl after the game. “That was down to how well they defended. You could feel it building at half time and the players were confident that if we could maintain those levels of intensity that we had shown in that first half that we would eventually get away from them and that is kind of what happened.
“I thought we were as tight as we have ever been, as good as we have ever been and defensively, it was a great performance.”
Munster did get themselves a try but that was countered by Sarries’ second touchdown as they controlled the closing stages despite losing Vincent Koch to the bin for a tip tackle in the final minutes.
Farrell was playing only his second match since that Calcutta Cup implosion and while he wasn’t at his authoritative best, the stand-off still kicked 22 points with six penalties and two conversions off the tee.
Billy Vunipola was jeered heartily every time the big fella carried the ball after his ill-considered tweets last week but he enjoyed the last laugh, scoring Saracens’ second try on 71 minutes which put this one beyond doubt. He looked like he was enjoying himself and why not, he earned the man of the match award on his 100th appearance for his club.
Vunipola was in the vanguard of Saracens power game. They don’t do anything very complex but the men in black are ruthless and relentless in equal parts. They run hard lines and slowly degrade even as resilient a defence as Munster bring to the party.
The Irishmen grabbed a lifeline on the one hour mark when the ball squirted out of a set scrum five metres from the Sarries’ line. The Saracens forwards thought they had done enough to earn a penalty but French referee Jerome Garces never likes to be second guessed and allowed play to continue.
Conor Murray picked Sarries’ pocket at the base of the scrum, Munster spread it wide right and, helped by a slip from Saracens’ fullback Alex Goode, Darren Sweetnam went over in the corner and JJ Hanrahan, on for Tyler Bleyendaal, added the extras superbly from the touchline.
Farrell missed a penalty on 66 minutes but his team had almost complete control of the match and ratcheted up the pressure until Vunipola’s try nine minutes from time ended any slim hopes that Munster still harboured of winning this one.