After Alberto Moreno put in one of the worst defensive performances in recent memory, many fans and pundits alike are calling for him to be replaced this summer.
Moreno, playing against his old club, was a liability all night long and was directly at fault for the first Sevilla goal, whilst also having a hand to play in the third.
Sevilla swarmed Liverpool early in the second half and overcame a 1-0 deficit at the break to run out 1-3 winners in Basel.
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Moreno is a fine attacking full-back, but his defensive work is nothing shy of atrocious at times, and Jurgen Klopp must find a more well-rounded player on the left for the future.
Speaking to BBC Sport, Mark Lawrenson said of Moreno: 'We have seen it so many times over the course of the season, the left back Moreno is good at getting forward but he cannot defend.'
The defeat was obviously a huge disappointment for Liverpool, especially considering the outstanding wins they had in the previous rounds of the competition against Borussia Dortmund and Villarreal.
Moreno was clearly not the only reason the Reds lost on the night and Sevilla definitely deserve a lot of credit for the way they played in the second half, namely Kevin Gameiro and Coke, who scored the goals and were a nuisance all night long.
However, for Liverpool to progress, they simply cannot carry a player who can be a liability to such a degree that it can cost them games at times. The Spaniard is almost better suited to playing left midfield, and might be retained as a squad player, but they need to sign a more solid and complete player at left back this summer.
So who should Jurgen Klopp look to bring in? With the way the German likes to play, the player would need to have adequate ball playing ability and attacking prowess, but solidity in defense is a must.
The 28-year-old played under Klopp at Dortmund and is a player the manager trusts and wouldn't cost an extortionate sum.
Schmelzer is a 16-cap German international, and is as solid a left-back as there is, with strong tackling ability and the necessary physicality to be a success in the Premier League.
He is an excellent crosser of the ball and has contributed six assists for his club this season. The advantages of a man who knows Klopp's system better than most are huge and it would be no surprise to see a bid go in for the Dortmund man.
The Wolfsburg man is likely to be a much sought after target this summer and is one of the best left-back's in Europe right now.
A set piece master and excellent attacking threat, Rodriguez can torch teams with his strong left foot and is calm and assured in possession, just what Klopp would look for in a player.
Additionally, the 23-year-old Swiss international is strong and dogged in defense, his stand-up tackling and intercepting abilities are top notch and is a very well rounded player.
Wolfsburg are not likely to sell him cheaply though, and Liverpool may look elsewhere if their asking price is too high.
Cresswell has had two excellent seasons with West Ham and arguably should have been given an England chance by now.
He is not flashy, but is confident on the ball and extremely solid in defense, whilst having a knack for scoring important goals.
The 26-year-old works extremely hard on-and-off the ball and is as good going forward as he is at the back.
However, being a relatively young English player, he is also not likely to come cheap and West Ham will certainly not be keen to sell one of their most promising players, but he would be a good addition to Liverpool's team.
Other options for Klopp could include Fabio Coentrao or Jonas Hector. Whichever player they decide to pursue, and it may be someone completely left field, an upgrade on Moreno is required as Wednesday's game made abundantly clear.
If YOU were Jurgen Klopp, what left-back would YOU sign for Liverpool? Have YOUR say in the comment section below!