It took less than 70 seconds for controversy to erupt between Liverpool and Manchester United at Anfield.
The away fans were sent into delirium just after the opening minute when Bryan Mbeumo fired the visitors into the lead with a powerful strike that beat Liverpool goalkeeper Giorgi Mamardashvili at his near post.
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As Mbeumo and his teammates wheeled off to celebrate, the cameras showed Liverpool midfielder Alexis Mac Allister lying on the ground and clutching his head.
Whenever a player suffers a head injury, referees have been instructed to halt play due to safety measures.
However, referee Michael Oliver did not stop the game as Mbeumo was allowed to race through and score.
Although some viewers and fans may have been left puzzled as to why Oliver didn't blow his whistle, Sky Sports commentator Peter Drury soon explained all.
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Why was Mbeumo's goal allowed despite Mac Allister's head injury?
"The information we're getting from the PGMOL is the referee didn't see the injury so therefore the referee couldn't stop the game," Drury said.
Had Oliver seen the incident, he could have paused the game and, as a result, prevented Mbeumo's goal.
To compound Liverpool's early woes even further, replays show no foul took place as it was actually a moment of friendly fire that caused Mac Allister to fall down to the turf.
As Mac Allister and Mbeumo jostled for a high ball, Liverpool centre-back Virgil van Dijk rose to head the ball away.
But in the process of jumping for the ball, Van Dijk elbowed the back of Mac Allister's head.
Thankfully, the Argentina international was cleared to continue but had to sport a rather unique look.
Alexis Mac Allister copped an accidental elbow from his teammate
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Mac Allister was a little worse for wear after he copped an elbow from Van Dijk...Credit: Sky Sports
Liverpool's Alexis Mac Allister is treated by club medical staff after suffering a head injury
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But was able to continue playing after being tended to by Liverpool's medical staffCredit: Getty
Alexis Mac Allister wears bandage
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Mac Allister sported a black bandage on his head after receiving treatmentCredit: Sky Sports
Upon returning to the pitch, Mac Allister donned protective headgear that looked something a synchronised swimmer would wear.
Although it was United who got off to a dream start, Liverpool could and perhaps should have equalised.
Cody Gakpo's cross took a slight nick off of Bruno Fernandes and clipped the post, with Mohamed Salah's effort on the rebound being saved by Senne Lammens.
British record signing Alexander Isak had a golden opportunity to level the score in the 35th minute when he was played in by Ibrahima Konate.
However, Lammens managed to divert Isak's effort with his boot, prolonging the Swede's wait for his first league goal this term.
Gakpo also came close to turning the ball into his own net late in the first half when he attempted to clear a cross from Fernandes, only for his effort to loop over the bar and land on the top of the net.