Jurgen Klopp was left raging after a pitch-invading fan took out his Liverpool players in the goal celebrations against Manchester United.
It was a special day for Liverpool, who are now just three points off the Champions League places after a recent resurgence.
But the only slight blemish for Klopp was when a supporter overstepped the mark after Firmino found the net.
The Brazilian striker, on as a substitute, supplied a smart finish past David de Gea and provided the perfect response to the news he will be leaving the club in the summer.
He was mobbed by his teammates as Anfield was sent into utter pandemonium yet again. One supporter got too excited and raced onto the pitch, inadvertently wiping out some of his heroes after slipping.
Both Andy Robertson and Curtis Jones were seen in discomfort while the Reds players were in a huddle.
Stewards were quick on the scene and took him away but as he was being escorted off, Klopp was absolutely livid and looked ready to explode on the touchline.
He had to be held back by the linesman and the fan was fortunate that Klopp never got closer to him.
Luis Diaz equalised for the 10-man Reds but in the 94th minute, the supporter ruined an attack by sprinting onto the field of play in the 1-1 draw.
He was apprehended by security but it halted Liverpool’s momentum and Klopp screamed at the individual while the fourth official tried to calm him down.
Next up for Liverpool is a Saturday lunchtime trip to Bournemouth, before they have the difficult task of salvaging a Champions League round of 16 tie with Real Madrid at the Santiago Bernabeu.
Liverpool surrendered an early 2-0 lead to be humbled 5-2 at Anfield in the first leg.