The Reds ran rampant over Swansea as the Swans continued their stay in the EPL cellar.
Liverpool stretched their undefeated Premier League run to 11 games, after they thrashed a helpless Swansea side 5-0 at Anfield. Coutinho's sixth minute stunner was followed by a second-half blitz; with two goals from Firminio, and one each from both Alexander-Arnold and Oxlade-Chamberlain.
The three points ensure that Liverpool remain 4th in the Premier League table, while Swansea remain bottom, now five points off safety.
Jurgen Klopp made four changes to the side that drew 3-3 to Arsenal. Trent Alexander-Arnold replaced Joe Gomez at right-back, Joel Matip returned from injury to replace Dejan Lovren at centre-back, Georginio Wijnaldum came in for the injured Jordan Henderson in midfield, and Alex Oxlade-Chamberlain returned to the starting lineup in place of Sadio Mané.
Swansea handed Oliver McBurnie his first Premier League start, leaving Tammy Abraham on the bench. Kyle Naughton and Leroy Fer, who were both injury doubts ahead of the game, started for the Swans. Jordan Ayew and Wayne Routledge also made their returns to the starting eleven.
Liverpool scored the first goal of the game with their first shot after just six minutes. Ayew lost possession midway in his own half to Firminio, the Brazillian then passed to it to Salah who fed it to Coutinho on the edge of Swansea's box, Liverpool's skipper took a touch before curling a sumptuous right-footed effort into the top corner, leaving Fabianski with no chance.
Ayew nearly made amends up the other end just three minutes later but his header lacked power, and Mignolet got down low to gather easily.
Robertson was close to extending Liverpool's lead a few seconds later. Firminio was again involved, the Brazilian's cut back found the onrushing Robertson who powered his shot just wide of Fabianski's net.
Despite their dominant start, Liverpool were struggling to create many opportunities thereafter, and as their intensity dropped Swansea started to gain more time on the ball, much to the frustration of the Anfield faithful.
Nevertheless, the Swans rarely looked threatening around Liverpool's box, and it was the Reds who should have scored the second goal of the game just before half-time.
Salah won the ball in midfield and sent Firminio away, the Brazilian did well initially getting past the challenges of both Mawson and Fernandez, however, he then dallied on the ball for too long and screwed his shot wide of Fabianski's goal.
Liverpool had the first real opportunity of the second-half in the 50th minute. Firminio fed Salah on the right, before the Egyptian cut onto his favoured left foot and released a low shot, but it was straight at Fabianski and the Pole made a routine stop.
Just a minute later and Jurgen Klopp's side finally extended their lead. Coutinho's free-kick from the left sailed to the back post and found the unmarked Firminio who volleyed in his first goal of the game.
13 minutes later and Alexander-Arnold scored his first Premier League goal. The 19-year-old reacted first to Mawson's clearing header, running onto the ball inside the Swans' box before thundering a shot in off the crossbar.
Just a minute later and Firmino scored his second and Liverpool's fourth of the game. Salah found space inside Swansea's box and selflessly rolled the ball to an unmarked Firmino who was left with a simple finish.
Soon after and Jurgen Klopp decided to take of the instrumental pairing of Mohamed Salah and Roberto Firmino for Dominic Solanke and Adam Lallana.
Liverpool compounded Swansea's misery in the 82nd minute. This time it was Oxlade-Chamberlain's turn to add his name to the scoresheet. Once again, Swansea's defense was nowhere to be seen, as the 24-year-old reacted first to Alexander-Arnold's blocked pass to caress his finish into the top corner from 12 yards out.
The result was never really in doubt after Coutinho had curled Liverpool into the lead in the first-half. Swansea struggled to create any meaningful opportunities throughout the 90 minutes, and their defense could not deal with Liverpool's scintillating attacking play, especially after they had tired in the second-half. Jurgen Klopp will be ecstatic with both the performance and the result which lifts his side back up to fourth in the league.