The Rivalry: Andy Robertson and Kostas Tsimikas vie for the left-back role at Liverpool

The Scotland international initially played second fiddle to Alberto Moreno in the left-back position when he first joined Liverpool under Jurgen Klopp.

Robertson had been bought from relegated Hull City for £10m in July 2017, although initially Liverpool had Monaco's Benjamin Mendy and AS Roma's Emerson Palmieri at No 1 and 2 respectively on their shortlist of targets, with the club's former head of data, Dr Ian Graham, revealing he had his doubts about the player.

"I was really not certain of Robertson's defending when he arrived," Graham recalled, only for Mendy to join Man City, while Emerson got injured, meaning the Reds moved for the third name on the list instead.

After waiting patiently for his chance in the first team, Robertson's big break came when Moreno got injured in December 2017, with the Scot grabbing it with both hands - and he has not looked back ever since.

In the intervening period, the 30-year-old has won virtually every single piece of silverware a player can in his club career, while racking up the joint-most assists by a defender in Premier League history along the way, level on 59 with his team-mate and full-back on the opposite flank at Anfield, Trent Alexander-Arnold.

He also scored crucial goals, such as the late headed equaliser en route to an astonishing 2-1 win at Aston Villa in November 2019 as Liverpool's march to a first league title in 30 years gathered unstoppable momentum.

Meanwhile, his cuff to the back of Lionel Messi's head in the Reds' unlikely Champions League semi-final comeback win against Barcelona at Anfield in May 2019 encapsulated 'Robbo' for many, the combative Glaswegian always with a point to prove.

Last September, Robertson even captained Liverpool as they came from behind to win 3-1 at Wolverhampton Wanderers, scoring their second late on - one of 11 goals in total he has for the Reds - a sign of his growing off-the-pitch influence at the club as part of the Reds' leadership group.

On the pitch, though, it is not too much to suggest he and Alexander-Arnold redefined the full-back role under Klopp, especially in the early "heavy-metal" part of the German's reign when, according to Graham, "It was Jurgen who said, 'My full-backs have to attack, we can fill in for his defence,'" when assessing options for the left-back role in the summer of 2017.

And boy did the duo attack, perhaps best seen with Liverpool's second goal in their 3-1 win against Man City at Anfield in November 2019 when Alexander-Arnold's raking cross-field pass released Robertson in space down the left flank and, from his inch-point centre, Mohamed Salah stooped to head home at the far post.

Durability, meanwhile, has also been another key hallmark of the left-back's time at Liverpool, until last season when he dislocated his shoulder playing for his country in a Euro 2024 qualifier in Spain in October, opening the door for Tsimakas to enjoy his longest first-team run since joining the club in August 2020 - only for the Greek to then break his collarbone against Arsenal two months later.

When Robertson did finally return to action at the end of January, he sustained a serious ankle injury playing for Scotland in March, only to continue playing through the pain as Liverpool chased a historic quadruple and Scotland competed at the Euros.

As a result, the defender crucially missed the start of new head coach Arne Slot's inaugural preseason, including the Dutchman's first matches in charge of the Reds on their tour of the US, meaning he has been playing catchup from both a physical and tactical viewpoint ever since.

So much so that Tsimikas has got the nod for Liverpool's Champions League contests with AC Milan, RB Leipzig and Bayer Leverkusen, the Carabao Cup tie with West Ham United, as well as Premier League encounters at Crystal Palace and Brighton & Hove Albion this campaign in a clear change from previous seasons when he acted solely as Robertson's understudy.

The Scot has also been heavily involved, starting Slot's first six league matches in charge and 15 in all competitions this season, although not without moments of difficulty with pundit Gary Neville observing in Liverpool's win against Chelsea in October: "There's something not quite right about Robertson in these opening 15 minutes or so," while he was also at fault for Arsenal's opening goal in the 2-2 draw at the Emirates later that month.

However, it was indicative the new manager went back to Robertson for their most recent encounter with Aston Villa at Anfield before the international break when he produced perhaps his best display of the campaign so far.

And the Dutchman himself certainly does not appear too concerned with the dilemma, explaining his chopping and changing merely as a consequence of the player's curtailed preseason: "I think his current situation is what you can expect if a player misses out on pre-season and a new manager comes in - you miss quite a lot.

"You have to go into a programme where you've missed the base tactically, when it comes to us [a new management team], and physically as well. It's not that big of a surprise that he's not playing all of the games because I think he was only on the pitch three or four days before he played the second friendly in our stadium [against Las Palmas on August 11]."

Slot, though, demands different things from his full-backs compared to his predecessor's attack-minded philosophy, meaning we are far less likely to read quotes like this from then-Manchester Utd manager Jose Mourinho after a 3-1 loss at Anfield.

"I am still tired just looking at Robertson. He makes 100-metre sprints every minute, absolutely incredible, and these are qualities," said the Portuguese after his final game in charge of United in December 2018.

In fact, Robertson is now far more likely to be found as an auxiliary centre-back alongside Virgil van Dijk and Ibrahima Konate when Alexander-Arnold pushes into midfield - as we saw happen last season - than bombing down the left wing as Slot opts for caution over chaos.

It is also important to recognise Tsimikas' own impressive form, however, which has made it a lot harder for Slot to ignore the Greek's first-team claims.

The 28-year-old has never let Liverpool down when called upon over the past four years, holding his nerve to convert the winning spot kick in the penalty shootout against Chelsea that decided the 2022 FA Cup final, before creating the dramatic late winner for Van Dijk in last season's Carabao Cup final against the same opposition.

With his wand of a left foot, Tsimikas has always been a threat going forward, as his big-chances created numbers this season show - he created Van Dijk's equaliser at San Siro in September and also caught the eye offensively in England's recent win in Athens - but he has also been rock solid at the back this campaign, again demonstrated by metrics such as goals conceded and interceptions.

All of which means the 'Greek Scouser', as Tsimikas has affectionately become known on Merseyside, is now no longer merely a backup to Robertson, but a viable and reliable option on the left-hand side of Liverpool's defence.

However, when it comes to knowing who Slot's actual first choice is, the proof will be in the manager's selection choices, as he himself recently admitted when asked that very same question.

"My lineups tell you what I think about this," he said, and who the Reds boss opts to start in the huge Premier League clash with Man City at Anfield on December 1 - live on - will be revelatory.

With Liverpool now facing a testing run of fixtures across three different competitions over the next month - they host European champions Real Madrid four days before Pep Guardiola's side visit Anfield - in reality both players are likely to get plenty of first-team action while the team continues to compete on multiple fronts.

But for now, let's just say reports of 'Robbo's' demise have very much been exaggerated.

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