In the early 1990s, full-backs were primarily expected to safeguard the defensive flanks, as their task on the pitch was more defense-minded than to attack. However, in recent times, the task of a full-back has expanded, as they are now expected to help both the left and right-wingers in attack.
Also, in some tactical set-ups, full-backs are expected to make forward runs, thereby creating more attacking options. In some cases, they are expected to deliver crosses into the box for the attackers to convert.
This list will rank the four such full-backs, who are the most valuable in the world right now, as per Transfermarkt.
#4 Nuno Mendes - €65 Million
While full-backs can have decent attacking proficiency with comparatively subpar defensive intuition, or vice versa, Nuno Mendes is a player with a good mixture of both. The Portuguese youngster is quite decent with his crosses in attack. Likewise, he is efficient in defense, as his potential to win the ball in a one-on-one circumstances is scrumptious.
At a considerably young age of 21, the left-back has registered 11 goal contributions in 69 appearances for Paris Saint-Germain. There's no doubt that he has a decent time ahead of him to improve further.
#3 Achraf Hakimi - €65 Million
The Moroccan is a typical description of a marauding modern-day right-back, as his capacity to progress with the ball and to deliver killer crosses into the penalty box is exceptional.
Similarly, when you watch him play, he enhances the number of attacking options that a team possesses. It is an advantage for an attacking team to have a player with this quality evidenced by Hakimi's 27 goal contributions in 91 games as a PSG player so far.
#2 Trent Alexander-Arnold - €65 Million
Currently, no full-back is as imaginative and precise as Trent Alexander-Arnold, as his deliveries in attack possess the proficiency to destroy any defensive set-up. As a right-back, Alexander-Arnold is a player with several qualities, as he could convert free-kicks, create chances in the final third, and shield the defense as well.
In 281 games for Liverpool, Alexander-Arnold has registered 89 goal contributions, and he merits his excellent market value.
#1 Alphonso Davies - €70 Million
What makes Alphonso Davies special and different from other players on the list is his blistering pace and capacity to outrun his opponent in attack.
In the defense, his pace is important as he uses the above to cover, which is key in averting attacking threats. The Canadian defender has registered 36 goal contributions in 166 games for Bayern Munich, and he's also the most valuable full-back in the world.