With the scores locked at 1-1 - virtue of goals from Sadio Mane and Jesse Lingard - the midfielder was introduced from the bench and quickly provided the invention that Liverpool were crying out for.
The Red Devils had began to frustrate their opponents in the final third, but Jurgen Klopp's decision to bring on Shaqiri started to expose cracks in the visiting defence.
Eventually, the breakthrough came on 73 minutes with the ball breaking in the penalty area from a David de Gea save and Shaqiri rifling home the rebound thanks to a deflection.
It sent Anfield into pandemonium and looked to kill off a United side who had started to play for a draw, but he wasn't finished there.
Liverpool 3-1 Man Utd
Playing a one-two with Roberto Firmino on the edge of the area, he tried his luck once again and defied De Gea with a deflection off of Eric Bailly.
It was the latest reminder of Shaqiri's remarkable impact at Liverpool since signing for a bargain fee form Stoke City this summer.
There were numerous critics of the move - including a certain Gary Neville - but they've all been silenced by his display against Jose Mourinho's men.
Martin Tyler's name for Shaqiri
Neville got to see the performance first-hand from the gantry, taking his seat alongside Jamie Carragher and Sky Sports stalwart Martin Tyler.
And Tyler had plenty to shout about during the encounter at Anfield and even devised an unlikely name for Shaqiri after his heroics.
Moments after Shaqiri had bagged his second goal of the game, Tyler bizarrely branded him: 'the chunky Swiss international.'
Well, that's one to way to put it and Liverpool fans couldn't held laughing across Twitter. Check out some of the reaction down below:
Chunky, Martin? Chunky?
Shaqiri is incredibly muscly for a player of his height and Liverpool fans do have a number of affectionate nicknames for him, with 'cube' proving one of the most common.
So, no doubt Tyler was going for something similar during his commentary but we're not sure this new label will be fondly maintained.
The player himself won't be complaining, though, and he can enjoy the coming days by reflecting on his match-winning performance against Liverpool's bitter rivals.
Although the disparity between the teams was wider than ever at the weekend, it was still a huge result and saw Liverpool maintain their Premier League lead.
And it was all thanks to their 'chunky' wizard in midfield.
Do you think Shaqiri should start for Liverpool? Have your say in the comments section below.