“Unbelievable. Sixteen. Wow,” was the verdict of coach Neil Critchley.
“His calmness and assurance, his decision-making, his intelligence without the ball, it was terrific.”
That was the day when he suddenly started being spoken about as potentially a first-team option this season.
All young players need some luck along the way and Hoever's arrived last month with the injuries to Alexander-Arnold, Joe Gomez and Joel Matip.
A week before Christmas, with Klopp short on numbers, the teenager was summoned to train at Melwood for the first time.
He found himself marking Mohamed Salah in a training game and senior professionals were blown away by how well he handled the Egyptian attacker. He's been with the first-team squad since.
As well as his obvious talent, Klopp has been impressed by the character and attitude of Hoever. There is no hint of arrogance. He's humble and grounded.
When Nathaniel Clyne declared that he wanted to leave on loan, Hoever's rise was one of the reasons why Klopp granted him his wish.
Jordan Henderson was initially set to start Monday's FA Cup tie at Wolves at centre-back alongside Fabinho in a depleted backline.
However, after the captain picked up a knock, Dejan Lovren was drafted into the side with Academy midfielder Isaac Christie-Davies promoted on to the bench.
Having been given the No 51 shirt and named among the subs, Hoever was dreaming of a short cameo but when Lovren pulled up lame, he was thrust into action after just six minutes.
Playing a 16-year-old at centre-back was an incredible show of trust from Klopp and his faith was rewarded. Hoever, who became the third youngster player in the club's history, provided one of the few positives on a bleak night.
A scholar earning £145 per week
Hoever will pen his first professional contract with Liverpool after he turns 17 on January 18, but for the time being he's still a scholar earning £145 per week. They don't get appearance bonuses.
He lives with a family in Liverpool with his parents travelling over from Amsterdam to spend time with him each weekend.
His English is improving fast and he is continuing with his studies at the Academy on Wednesday afternoons.
His Instagram following has shot up to over 112,000 over the past week after his message that read: “A disappointing result last night but happy and proud to have made my debut for Liverpool.”
But don't be fooled by the Twitter account in his name, that's a fake and he's not on that platform.
History is full of cautionary tales about the dangers of getting carried away with young starlets.
Jerome Sinclair, the youngest player in Liverpool's history, is currently struggling to get a game on loan at Sunderland in League One.
Hoever will go back to playing for the Reds' under-23s over the coming weeks. Physically, he's not yet ready for the Premier League but Monday night was another giant leap forward for him.
Liverpool's recruitment staff bagged a gem with Hoever. And when Hunter pursues more young elite European talent this summer, Hoever's remarkable rise will strengthen his hand when it comes to arguing that Anfield should be their destination of choice.