Full-backs have grown into the key figures for clubs in the modern era of football. Their roles have remarkably evolved over the years. Every team that has achieved something noteworthy over the last half a decade and more has a sublime pair of full-backs — Marcelo/Dani Carvajal of Real Madrid, Andy Robertson/Trent Alexander-Arnold, and the like.The act as auxiliary attacking outlets down the flanks, always bombing down the wings on the counter or even by providing width to allow attackers to drift in-field. While in some cases, such as that with Marcelo, for instance, they act as wide-playmakers, continually passing and receiving the ball in wide areas and looking for a final ball to find their teammates.55 - Marcelo Vieira has made 55 assists in La Liga, at least 24 more than any other current defender in the competition. Solidarity. pic.twitter.com/jC5Otemh1n— OptaJose (@OptaJose) September 28, 2018The demand for full-backs has noticeably grown in the recent past, with clubs such as Manchester City, Barcelona, and Real Madrid having invested in recruiting technically gifted wide defenders in numbers. With this growing demand, the expectations of full-backs have grown vastly as well, as players playing in those positions need a particular skillset to command their flank.While many full-backs have displayed that skillset to play out wide, some stand above the rest due to their ability to dominate their side both offensively and defensively for the entirety of the 90 minutes.Here, we take a look at the five best left-backs in world football at the moment.#5 Jordi Alba | BarcelonaFC Barcelona veteran Jordi AlbaBarcelona veteran Jordi Alba has been one of the most dependable left-backs in the world since his move to the Nou Camp in 2012. The €14m man has grown into his role at Barcelona and contributes noticeably to both their offence and defence.Alba has a unique understanding on the pitch with Lionel Messi, and the interplay between the two players is sublime to watch. Quick off the mark and one of the quickest players in his team, Alba boasts a commendable recovery pace as well, something which helps the Catalans when they're caught on the counter.12 - Jordi Alba has provided 12 assists in all competitions in 2018/2019 season, more than any other campaign in his career on the Top Flight. Trays pic.twitter.com/An1KGhH0GP— OptaJose (@OptaJose) January 30, 2019The 31-year-old is comfortable playing in a high line and is a reliable crosser as well, notching up two goals and five assists in LaLiga Santander this season. Alba averages a whopping 70 passes per game in the league from left-back, further highlighting how comfortable he is with the ball at his feet.The all-conquering Spaniard will go down as one of the most respected left-backs over the last decade. Although his powers have begun to wane due to a few questionable performances in Europe, he still has a lot left in the tank to offer.#4 Alex Telles | FC PortoTelles has been in surreal form for FC PortoOne of the most in-demand left-backs in the world at the moment, Alex Telles is fresh off a stunning season with FC Porto en route their domestic double. The 27-year-old took some time to settle into European football with a couple of short spells at Galatasaray and Inter Milan.However, once he settled down in Portugal and made Porto his home, he's grown into one of the most well-rounded, all-action left-backs in the world. Whether it's in attack or while shutting an opponent is out, Telles has impressed profoundly with his plays in 2019/20. What sets him apart from many other full-backs is his expertise in dead-ball and set-piece scenarios, and an eye for goal.Alex Telles in the league since 2017/18:❐ 76 games❐ 207 chances created❐ 134 interceptions❐ 25 assists❐ 11 goalsMarcos Alonso & Emerson combined since 2017/18:❐ 100 games❐ 96 chances created❐ 124 interceptions❐ 9 assists❐ 10 goalsThose set-pieces help. 😉 pic.twitter.com/5AVOlpkRd4— Squawka Football (@Squawka) January 3, 2020Although he is Porto's designated penalty taker, his numbers are absolutely surreal, having racked up eight assists and 11 goals in 31 Liga NOS games. Key passes (1.8 p90), shots on goal (1.3 p90), crosses (2.3 p90), and tackles (1.1 p90) — Telles can do it all.It comes as no surprise that the likes of PSG and Chelsea are hot on Telles' tracks and hope to snap him up ahead of the 2020/21 season. With his contract running out soon and the 27-year-old entering his prime, it won't be long before a top club come calling for him.