It was yet another moment for Alex Inglethorpe and his staff to savour.
Only a friendly? Not to the young Scouse star, nor to those who have helped make him.
For Liverpool's Academy, Alexander-Arnold's meteoric rise is a source of immense pride, not to mention inspiration, for those seeking to follow in the 20-year-old's footsteps.
In the past 18 months alone, the West Derby-born full-back has established himself as an Anfield first teamer, scored for club and country, played in a Champions League final and at a World Cup. He has been shortlisted, along with the likes of Kylian Mbappe, Phil Foden and Justin Kluivert, for the prestigious European 'Golden Boy' award for 2018 - the second year in a row he has been recognised.
What a story, what an example to the next generation of young stars emerging at Kirkby. Liverpool's first team is where the glory is at, but below it there is plenty to get excited about.
Here, Goal takes a look at the latest goings-on at the Reds' Academy - and picks out a few names to keep a close eye on in the coming weeks, months and years...
Curtis Jones - Liverpool Under-23s
What Curtis Jones lacks in experience, he more than makes up for in confidence.
It took a little more than five minutes for the young Scouser - born and raised on the outskirts of the city centre - to announce himself to Liverpool supporters.
Jones was just 15 years old when he was called up by Neil Critchley, then the club's Under-18s coach, for an FA Youth Cup tie with Crystal Palace at Tranmere Rovers' Prenton Park ground in December 2016. He'd played for the 18s before, against Middlesbrough in a league match, but this was different. A big game for the Reds, for sure. In the team that night were the likes of Rhian Brewster, Adam Lewis, Yan Dhanda and Kamil Grabara.
Nervous? Not Jones. His first notable action in the game was to make what fans will now recognise as a trademark run down the left channel, bamboozle a defender and then produce a Rabona-style cross into the danger area. The crowd, a healthy one for a game of its type, purred in appreciation.
Jones would score later in the game, and Liverpool would eventually progress after a penalty shootout. The teenager's progress has accelerated since.
He doesn't turn 18 until January, but he's already a part of Jurgen Klopp's first-team squad, training at Melwood while picking up game-time (and experience) with Critchley's Under-23s and playing in the UEFA Youth League for Barry Lewtas' Under-19 side. He's a precocious talent.
He's been close to a senior run-out, appearing on the bench for the Merseyside derby at Goodison Park last April and again in the Carabao Cup clash with Chelsea at Anfield in September. On Liverpool's tour of the USA in pre-season, he was one of the standout performers.
"He's pretty good, eh?" Klopp told Goal when we sat down for an exclusive interview on that tour. The Reds boss knows he has, potentially, something special on his hands in Jones.
“Curtis is a proper Scouser," he said, offering an insight into the inner confidence and belief which sets the attacking midfielder apart from many of his peers. "I don’t know if I have the right words, but he is not shy to say a few things and probably that’s a surprise for one or two players!"
In terms of talent, Jones' is obvious. Steven Gerrard talked about building his Under-18s team around him last season, and Jones flourished under the guidance of the Reds legend. Versatile enough to play in a number of positions across the midfield and forward line, his control, skill and dribbling ability stands out a mile. There are similarities with a young Philippe Coutinho in the way Jones drifts out to the left-hand side and the manner in which he can glide past defenders with a swivel of the hips and a sharp change of pace. Like Coutinho, though, the big development to come is in terms of decision making and end product.
“He is a tall boy but still very mobile, good at dribbling and stuff like that," Klopp says. "But now we need to make sure he finds the right moment to pass the ball - and dribbling is not for dribbling, it’s to change the situation in a better way and then to pass the ball.
“But it’s easier to train that than to show somebody how to dribble, which is quite natural. It’s cool. Physical-wise he is good and has talent as well, but there is a long way to go."
This season, Jones has moved from Under-18s football to Under-23s. It has not been an easy transition - Critchley's side lack a goalscorer and have generally been underwhelming so far. Jones is a regular starter, but even he has struggled at times. Liverpool currently sit eighth in the Premier League 2 table having won just three of their 10 league games, though on Wednesday evening they begin their Premier League International Cup campaign against Villarreal at Kirkby.
As for the longer term, we can expect to see much, much more from this assured, hugely-talented youngster. At 17, he's had a taste of what could lie ahead if his application is correct.
“Every young lad’s dream is to break into the first team," he said back in August. "But saying that, if I want to catch the eye of the manager as an attacking player, I definitely think I’ll need a lot more goals and a lot more assists.
“You see with Mane, Salah, Firmino, they’re causing teams a big problem and scoring a lot of goals. If I want to get the breakthrough and catch his eye, I need to be matching that.”
Wise words from one so young. Now, the challenge is to back them up with actions.
Other academy talking points
- While the Under-23s stutter, Barry Lewtas' Under-18 side go from strength to strength. They've won 13 of their 15 games in all competitions this season, scoring an incredible 50 goals in total. Strike duo Paul Glatzel and Bobby Duncan have been responsible for 23 of those. Both were on target in a thrilling 4-3 win over Everton at Kirkby recently, with Jack Bearne heading in a late winner. Lewtas' boys sit second behind the Blues in the Premier U18 League table, but have a game in hand on their rivals which would take them to the top if they were to win it. Next up, Derby at home on Friday.
- In the UEFA Youth League , Lewtas is making a similarly positive impression. Liverpool have taken 10 points from a possible 12 after beating Red Star Belgrade home and away. They are guaranteed to progress from their group, and can top it by avoiding defeat away to Paris Saint-Germain next Wednesday. That would guarantee them a place in the last 16 - finishing second would send them into a play-off.
- The development of young goalkeeper Caoimhin Kelleher has been recognised with a first senior call-up for the Republic of Ireland. Kelleher was an unused substitute for the recent games with Northern Ireland and Denmark, having impressed Roy Keane - a recent visitor to Kirkby - with his performances at youth level. Liverpool have a couple of other young Irish talents, with Conor Masterson and Corey Whelan both having picked up youth caps.
- If Neil Critchley has cut a frustrated figure at times this season, then his side's inability to convert penalties will not be helping his mood. The Under-23s missed two in their recent draw with Burnley, with both Rafa Camacho and Bobby Adekanye failing from 12 yards. Adam Lewis blazed one over the bar earlier in the season against Tottenham at Anfield, and was denied from the spot for the Under-19s in the UEFA Youth League win over Red Star Belgrade. More practice needed at Kirkby, one suspects.
- Still, at least Critchley could reflect on a positive international break for his players. Striker Liam Millar featured for the senior Canada team, picking up his fourth cap against St Kitts and Nevis, while Curtis Jones , Rafa Camacho and Kamil Grabara all picked up caps for their respective countries at youth level.
Premier League 2 results
October 7 - West Brom 1-0 Liverpool (Premier League Cup)
October 21 - Liverpool 2-3 Derby (goalscorers Virtue, Christie-Davies)
October 29 - Blackburn 2-1 Liverpool (Virtue)
November 3 - Liverpool 3-1 Leicester (Virtue, Solanke, Christie-Davies)
November 11 - Liverpool 1-1 Burnley (McAuley)
UEFA Youth League results
October 3 - Napoli 1-1 Liverpool (Adekanye)
October 24 - Liverpool 2-1 Red Star (Camacho, R Williams)
November 6 - Red Star 0-2 Liverpool (Jones, Lewis)
Premier U18 League results
October 6 - Liverpool 1-0 Manchester City (Duncan)
October 20 - Wolves 0-3 Liverpool (Glatzel 2, Dixon-Bonner)
November 1 - Liverpool 4-3 Everton (Duncan, Glatzel, Clarkson, Bearne)
November 10 - Liverpool 6-0 Reading (Glatzel 2, Duncan 2, Clayton, Dixon-Bonner) - Premier League U18 Cup