In order to resume normal service and more importantly keep pace with Group E leaders Napoli, the Reds had to come out as winners.
And they accomplished the task in lethal fashion, with the returning Oxlade-Chamberlain getting in on the act as early as the second minute. Genk thought they had restored parity midway through the first half, but VAR ruled out Mbwana Samatta's goal for offside.
Oxlade-Chamberlain portrayed his impeccable technical ability with a gorgeous strike just before the hour mark. The talismanic duo of Mane and Salah rounded off an all-round display with well-taken goals to put the result way beyond doubt.
Substitute Stephen Odey snatched a consolation goal late on, but Liverpool held firm to take home maximum points.
On that note, we look at five players who put in commendable shifts to grant Liverpool a morale-boosting victory.
#5 Mohamed Salah
Mohamed Salah was far from his clinical best on his return from a minor strain. He squandered many opportunities of picking the right ball or netting by himself. There were a lot of chances that came his way throughout the course of the 90 minutes, but the Egyptian looked rusty, indecisive and scrappy with his touch.
However, it just takes a moment for the mercurial magician to chalk his name on the contribution sheets. That's what Salah is all about at times. That's what great players hold in their armory.
He just needed a moment or two to completely take the game away from Genk. On the back of a fine recovery, he received the ball from Roberto Firmino. With all the time and composure in the world, the winger slid a pass-through to Mane, who dispatched it imperiously with a chip.
Salah's magical feet shone when he spun off two challenges on the edge of the box and slotted home the fourth to leave the hosts stranded.
#4 Naby Keita
For most part of the game, the Liverpool full-backs and defenders operated in the opposition half. They dominated in every aspect of the game during the possession, outnumbering the opposition midfield and taking the attack to them with urgency.
Naby Keita, right from the outset, remained a catalyst to Liverpool's quick passes, pacy approach and comprehensive attacking.
The Guinean impressed one and all with his fluency with and without the ball. He looked safe and collected in possession, as he picked the gaps between the opposition midfielders, drove forward with purpose and imposed a silky touch to the way the Reds went about their business.
Keita worked his socks off, winning key battles in the middle-thirds of the pitch and occupying fine positions to intercept and perceive the next attempted pass from Genk.
He wasn't afraid to pick an incisive, risky pass. The inch-perfect ball to Firmino in the build-up to the second goal served as a true testament for the same. Could this be his year in a Liverpool shirt?
#3 Roberto Firmino
After a rare substandard display over the weekend against Manchester United, Roberto Firmino was back to his crafty best against Genk.
The Brazilian was all over the opponents at times, picking up loose balls, linking up play and cleverly finding teammates in empty areas of the pitch. His awareness, ability to free up space or drag defenders out led to massive openings, as exemplified in the second and fourth goal.
Firmino, of course, ran the races and just didn't stop offering his 100% until the final whistle. He occupied dangerous positions more often than not when not involved in the attack at first, and proved to be a menace for the ones marking him inside the 18-yard box.
The forward was intelligent without the ball, but with it, it seemed even better on the eye, especially when he set up a Sadio Mane chance and Oxlade-Chamberlain's second of the evening.
While Jurgen Klopp opted to rest Georginio Wijnaldum and Jordan Henderson, he couldn't resist the prospect of continuing with the ever-so-reliable Fabinho at the heart of a three-man midfield.
And on his 26th birthday, the midfielder ran the show from the center of the park and disposed of danger without any fuss.
Fabinho covered good ground, kept the opponent's attacking potential in check and stayed alert throughout. He had to work more with the ball, owing to Liverpool's dominance in possession.
On an overall note, Fabinho put in a massive effort and even rewarded himself with a fine-tuned pass to Oxlade-Chamberlain for the opening goal.
He's slowly becoming one of the most dependable players in this Liverpool squad, if not quintessential. That bit of assurance and license he offers to the more attack-minded midfielders is praiseworthy and a piece of excellent execution, to say the least.
#1 Alex Oxlade-Chamberlain
He was widely regarded as one of the brightest prospects in English football, but Alex Oxlade-Chamberlain has struggled to match the diagnosis made regarding his potential. Mainly due to injuries, one would argue, as the midfielder was making his first UCL start since April 2018.
He brought a bit of dynamism and flamboyance down the right-hand side of the midfield, something we wouldn't associate with Henderson in the same position. And boy, he looked full of purpose.
The two goals themselves, serve as proofs, as Oxlade-Chamberlain epitomized his potential and technical prowess. He made it look so easy when upon being fed by Fabinho, launched a fierce yet effortless strike into the left bottom corner moments after kickoff.
Just when you thought he had marked his return with a stupendous display, 'Ox' produced a moment of magic for his second, lofting his shot with the outside of the boot beyond a hapless Gaetan Coucke.
Besides the goals, Oxlade-Chamberlain's work rate was infectious, and so was his link-up down the right with the winger and the full-back.
The interchangeability and flexibility with respect to positions in this Liverpool setup worked wonders for him, as typified by the manner in which he scored both his goals.