It is hard to believe the England international is only 21 years of age considering he has already amassed 125 appearances for his boyhood club.
The right-back made his debut during the 2016/17 season, but it wasn't until the Reds' run to the Champions League final the following season when he put himself on the map.
Alexander-Arnold hasn't looked back since, and alongside fellow fullback Andy Robertson, has become a vital component in Klopp's system, responsible for not only defending but creating chances with precision crosses.
A former midfielder at youth level, the Liverpudlian collected a Champions League winners medal and broke the Premier League record for assists from a defender with 12. This season he was nominated in the top 50 for the Ballon d'Or, cementing his status as one of the best right-backs in the world.
Whelan was proud to watch Alexander-Arnold achieve his life-long dreams, with the pair remaining close friends after coming through the ranks together at Liverpool.
Asked if knew Alexander-Arnold's world-class potential as a youngster, Whelan told Tribalfootball.com: "I could yeah. I definitely could but obviously people looking from the outside looking in, he appeared on the scene and it kind of happened from there.
"But from playing with each other when we were younger, you know he's got, as you see on tv every week, an enormous amount of ability.
"He's improved things of his game that he knew he needed to improve and now he's probably one of, if not, the best right backs in the world at the minute.
"I could definitely vouch that when we were younger he definitely had certain things other players didn't have. So it's no surprise to see him doing well right now."