Manchester United's Luke Shaw runs past Thiago AlcantaraThere are several incredibly talented left-backs in the Premier League and we're starting to see the best of some of them now.When there is a conversation about the greatest left-backs to have played in the Premier League, names like Dennis Irwin, Ashley Cole, Patrice Evra and Stuart Pearce among several others come to mind.Of late in the Premier League, there has been a tendency among most teams to switch to a more expansive style of football.A lot of attention and focus is given on building from the back and as such, full-backs and wing-backs play a big role in connecting the defense and the midfield and then the midfield and attack as they almost become primary ball carriers.The full-back's primary duty is to help out in defence as opposed to a wing-back. However, that doesn't mean that they ever stop shuttling back and forth down their flanks. It is one of the toughest jobs on a football pitch.On that note, let's take a look at the top five left-backs in the Premier League this season.#5 Stuart DallasPatrick Bamford and Stuart DallasPerhaps the most versatile player on this list, Dallas has made more than 200 appearances playing in a variety of roles ranging from left-back to midfield to right-back.One of Leeds United's most reliable players on the football pitch, Stuart Dallas has made the majority of his appearances this season at left-back. Though their overall defensive performance needs improvement, Leeds United continue to be menacing whenever they break.Dallas has been excellent in that sense for Marcelo Bielsa's side and has scored five goals and provided two assists this season. His contributions have come from a variety of roles but he has been pretty formidable at left-back this season.Stuart Dallas has as many premier league goals as Anthony Martial and Mason Greenwood combined this season, playing as a left back.Levels to this game#lufc #MUFC pic.twitter.com/Cnokn2QgEm— bielsa's high press (@russianbot3004) March 2, 2021#4 Kieran TierneyWest Bromwich Albion v Arsenal - Premier LeagueScottish international Kieran Tierney has been one of the bright spots in an otherwise dull season for Arsenal. He has been one of their most influential players on the pitch and has been an unlikely attacking outlet for the Gunners.What sets Tierney apart is his ability to perform his defensive duties just as well as he can attack. He has also produced impressive performances playing for a struggling Arsenal side which means that if the Gunners can invest wisely and bolster their squad, we'll undoubtedly see Tierney up his levels as well.Tierney has a goal and an assist in the Premier League and judging him on the basis of those numbers would be quite reductive as most pundits are in agreement that Tierney is one of the best left-backs in the Premier League.Pierre-Emerick Aubameyang on the fastest players in the squad: "Top three, apart [from] me, you put me on the side, I think Kieran Tierney. He asked me to do a race against him because the stats are talking for him, maybe he is quicker than me, so let’s do it." pic.twitter.com/3imh9HZmL7— AFTV (@AFTVMedia) March 7, 2021