Luis Diaz put the ball in the back of the net for the Reds in the first half, but his goal was wrongly disallowed for offside upon consultation with the VAR, causing widespread outrage among fans and pundits.
PGMOL released a statement after the game confirming that an error had been committed, while reports claim that PGMOL chief Howard Webb got in touch with Liverpool to apologise for the debacle.
PGMOL's statement read: "PGMOL acknowledge a significant human error occurred. PGMOL will conduct a full review.
"The goal by Luiz Diaz was disallowed for offside by the on-field team of match officials. This was a clear and obvious factual error and should have resulted in the goal being awarded through VAR intervention, however, the VAR failed to intervene."
In response to PGMOL's admission, Liverpool released their own statement, highlighting the 'unsatisfactory' standard of officiating.
The statement, available on the club's official website, reads: "We fully accept the pressures that match officials work under but these pressures are supposed to be alleviated, not exacerbated, by the existence and implementation of VAR.
"It is therefore unsatisfactory that sufficient time was not afforded to allow the correct decision to be made and that there was no subsequent intervention.
"That such failings have already been categorised as 'significant human error' is also unacceptable. Any and all outcomes should be established only by the review and with full transparency.
"This is vital for the reliability of future decision-making as it applies to all clubs with learnings being used to make improvements to processes in order to ensure this kind of situation cannot occur again.
"In the meantime, we will explore the range of options available, given the clear need for escalation and resolution."