Former Liverpool captain Graeme Souness called for Cannonier and his family to be given tickets to the Champions League final and said on Irish television: "Watch this, we will circle him (the ball boy).
"It goes out for a corner. They are following the ball... watch the ballboy here. He is already on the spot.
"He puts it down now. He goes to walk away and he realises there is a few dopes gone to sleep.
"They have all turned their back on it. That is criminal, criminal for a professional footballer."
In a delightful piece of symmetry, pictures surfaces of academy graduate Alexander-Arnold as a ballboy at Anfield in 2014.
The 20-year-old right-back is due to play in his second Champions League final in as many seasons, and produced possibly his finest performance in a Liverpool shirt in their remarkable comeback.
Cannonier is also a promising Liverpool academy player, sometimes playing two years above his age.
The multi-ball system is used in the Champions League and international tournaments, but not in the Premier League where only one match ball is in play during the match unless the referee calls for another.