Paris Saint-Germain's French striker Kylian Mbappe celebrates scoring the second goal during the UEFA Champions League group C football match between Liverpool and Paris Saint-Germain at Anfield in Liverpool, north west England on September 18, 2018.
Klopp's side raced into a two-goal lead against the star-studded French champions thanks to Sturridge's clinical header and a James Milner penalty.
Thomas Meunier's low volley cut Liverpool's lead in the first half and the Belgium global suggested PSG should consider following the Reds' tactical plan.More news: Syria's Assad blames Israel over downing of Russian plane
However, Firmino came on as a second-half substitute to scored a superb victor in injury time to seal three points for Jurgen Klopp's side.
Last night, Liverpool and PSG produced an unbelievable game to remind all of us why we miss Europe's foremost club competition.
"They changed a bit of the system, we expected it and didn't think too much about it", Klopp told BT Sport.
Daniel Sturridge was far more effective in that regard, losing possession just seven times. They have garnered maximum points from 5 games they have played so far in the league.More news: United States ready to negotiate with North Korea 'immediately': Pompeo
"We changed the system because we expected a change from them".
Salah shot narrowly over before PSG made a change, Di Maria replaced by Eric Maxim Choupo-Moting, and then Mane steered a low effort across goal from an acute angle.
"Neymar on the left was not a bad idea and makes defending more hard, we needed more focus and we felt we did really well".
'The fact they have still won their first six games of the season will strike fear into their rivals'. When the ball was passed back to him, his distribution was solid as you could see he was trying to find the long balls down the middle to our front three which is always a positive sight.More news: Macron: Political leaders pushing for Brexit are 'liars'