Leading 13-0 against the run of play, the five-time English champions took swift advantage of the dismissal of Byron McGuigan to score through Sean Maitland in the right corner.
But the try was all about Vunipola’s attacking skills as the bulldozing number eight showed no ill-effect from the knee injury that has kept him out for four weeks by dummying through midfield and sending Sean Maitland over with a long, floated pass.
At 18-0 down there was no way back for Sale, who had to play the last 35 minutes with 14 men after McGuigan combusted amid minor provocation from Nick Tompkins, striking the Wales centre from behind and then throwing him to the floor.
The Sharks showed commitment to stay in the fight and were rewarded with tries by Ben Curry and Raffi Quirke, but there was no way back against opponents who were magnificent in defence.
Saracens climbed to second in the table and it looked ominous when they built a 10-point lead in the first quarter with Vincent Koch finishing a line-out drive and Alex Lozowski landing the conversion and a penalty.
But Sale were also their own worst enemy as AJ MacGinty kicked out on the full and Quirke spilt forwards a simple catch just outside his 22, inviting pressure on to the Sharks.
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Although trailing the scoreboard, they continued to control possession and territory as they attacked with purpose and at speed.
Once again, however, they shot themselves in the foot as a short-range scrum ended in a penalty awarded against them and then another 10 metres were conceded for backchat to referee Thomas Foley.
MacGinty was denied Sale’s opening points by the woodwork but the one-way traffic continued with Saracens unable to escape their half, although a dummy and run from Vunipola did eventually get them moving forwards.
It proved to be the launchpad for another sucker punch as Saracens moved downfield and forced a penalty which Lozowski sent between the uprights.
Sale lost captain Jono Ross to a failed head injury assessment, ushering Tom Curry on the pitch, and the second half began with the Sharks camped on the home whitewash in their most threatening period in the match.
But the attack came to a violent halt when McGuigan lost his head and was shown a red card.
It took only four minutes for Saracens to take advantage of McGuigan’s absence as Vunipola showed his vision to create a hole in midfield and then send Maitland strolling over.
The home defence had been watertight but a loss of concentration in the 62nd minute allowed Ben Curry to dart over from five metres out and the score revitalised the 2006 champions.
A knock-on ended their next attack and once wing Rotimi Segun had placed Saracens back on to the front foot, Alex Goode produced clever pass to send Max Malins over.
Quirke replied for Sale but the their fightback had already been extinguished.
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