That’s according to a man who once played for Liverpool in the same position, Jose Enrique.
Robertson and Alexander-Arnold are key members of a Reds side that has won three major trophies in the last 12 months, while also amassing a 97-point haul in 2018-19 and setting a record-breaking pace in this season’s Premier League title race.
And Enrique believes the duo’s form over the last two years makes them football’s finest in their respective roles.
“Definitely. In the last two seasons, definitely,” Enrique replied, when asked if Robertson is the leading left-back on the planet on LFCTV’s Legends in Lockdown.
“For me, he has everything. He has energy, the energy he has he makes you tired just looking at him sometimes in the games! How much he goes up and down the wing is unbelievable.
“The intensity, I love the intensity [in how] he plays the game, it’s unbelievable as well. And obviously the end product he has is really good as well, his crosses are amazing.
“He defends well as well, so he’s the full package really and I believe he’s the best left-back in the world for the last two years, definitely.”
Watch: Enrique and Molby star on Legends in Lockdown
On Alexander-Arnold, the Spaniard stated: “The same as I say with Andy Robertson, I say with Trent: he’s the best right-back in the world for the last two years as well and he’s only 21 still.
“So many people want to know, ‘Let’s see if he can play in midfield’ and everything, and I say, ‘Why do you want to change him when he is the best already in his position, he’s still only 21 and he can improve so much in the position?!’
“Because he can still improve a lot, so imagine when he improves!”