The teenager burst on to the scene last season, making 12 appearances in all competitions, and he has gone from strength to strength this term having played nearly 30 games so far.
With Nathaniel Clyne out, Liverpool were looking like they may experience somewhat of a right-back crisis earlier in the season. However, not only has Alexander-Arnold done well to step into the void left by Clyne, he has made the position his own in Jurgen Klopp's starting XI.
It was reported by the Mirror that the club had already intended to increase the 19-year-old's wages following his performances this term. Yet his excellent showing against Manchester City, which saw the Reds knock the Premier League champions out of the Champions League to reach the semi-finals, prompted a fast track new deal as the club look to ward off interest from clubs further afield.
There will be stiff competition for right-back when it comes to England this summer, with Kyle Walker and Kieran Trippier also vying for a spot in Gareth Southgate's World Cup squad. However, there is no doubt that the Liverpool youngster is now right in the frame to be picked, having proved he can perform to the highest standard against the best calibre of opposition.
Klopp will be happy to tie down his young star for the next four years, as he looks to continue masterminding what has been a magnificent turnaround at Anfield since his arrival.
Should the German retain the core of his team, with the likes of Mohamed Salah in the form he is currently experiencing, the Manchester clubs may have another team to contend with when it comes to the top flight title in England.