Andrew Robertson is used to dealing with setbacks. At the age of 15, the diehard Celtic fan was released by his beloved club after they chose to go in a different direction following the death of Tommy Burns, who headed the club’s academy. Robertson was viewed as too small and physically weak to succeed.

If joining Third Division Queen’s Park kept Robertson in the game, the reality was bleak. He became an amateur player, working on the phone lines at Hampden Park selling tickets in order to make money and fund his football. He was close to applying to go to university or trying to become a PE teacher before Dundee United approached Queen’s Park for his signature.

From then on, Robertson’s career looked to be on a continuous rise. He impressed enough in the Scottish Premier League – named PFA Scotland Young Player of the Year in 2014 – that a host of English teams scouted him before then-Premier League Hull City signed him for £2.85m in July of the same year. Four months later, he scored for Scotland against England at Celtic Park.

By 2017, and at the age of 23, Robertson was ready for his big career move to Liverpool. Jurgen Klopp described him in glowing terms, claiming that there was no limit to Robertson’s ambition.

“For Andrew, this is another big step on what has been a quite incredible personal journey in a very short space of time,” Klopp said. You can say that again.

In comparison with the devastation of being released – “At that young age you don’t really know how to deal with it” – falling out of favour at Liverpool was closer to blip than crisis. Yet at the beginning of December, Liverpool’s £8m summer signing had played only three times for his new club.

In November, Klopp’s assessment of Robertson hardly screamed optimism: “People will say: ‘Why did you sign Robertson, because he is here and not playing?’ Because he has to learn, but there is no problem. We are in conversation, talk about it and he has to improve. He cannot start so often as he would thought from the beginning. It’s all about improvement and then to be ready for the moment you are used.”

Most worrying was that Robertson had been left out of the matchday squad completely on 11 separate occasions. Klopp prefers to use multi-functional players on the bench rather than specialists. With James Milner experienced in that role and as a central midfielder, Robertson sat in the stands.

With Alberto Moreno vastly improved and Joe Gomez also able to deputise at left-back, Robertson was again becoming a forgotten man. A report in The Sun claimed that he was fighting to leave Anfield on loan in January, although Klopp was insistent on blocking any exit.

Whether or not that report was accurate, the insinuation was obvious. A dream move was in danger of going sour.

In Robertson’s defence, there is no indication that he dealt with the situation badly. “If I don’t play I’m always annoyed, but I’ve learned over the years to put that frustration into being better in training instead of taking the hump,” he told BBC Sport in October. Work harder, be better; the Robertson mantra. It is precisely what Klopp was asking for.

December brought good fortune, but good fortune happens to the hardest workers. Robertson impressed against Brighton after Moreno was rested, and the Spaniard was substituted in the first half of the 7-0 win over Spartak Moscow four days later. Klopp confirmed that Moreno would be absent for six weeks with an ankle injury.

Only the most honest footballer would admit to celebrating an injury to a teammate, but one man’s bad luck is another’s opportunity. Robertson was selected for the Merseyside derby the following weekend, and has now started seven of Liverpool’s last eight matches. There is no guarantee that Moreno will take his place when fit.

Andy Robertson was excellent for #LFC tonight. Five tackles, four clearances, one interception, eight possession gains. Most touches. 81.8% of his duels won… Was up for it and gave it everything he had. — Melissa Reddy (@MelissaReddy_) January 5, 2018

Against Everton on Friday, Robertson was arguably the game’s best player. Yannick Bolasie was Everton’s most dangerous attacking outlet, but Robertson dealt with the threat impeccably. He had more touches than any other player, completed more tackles too and had the second best passing accuracy of any starter.

Full-backs are increasingly judged on their attacking, and there is no doubt that Robertson’s crossing can be an effective tool. But it is the defensive work that sets him apart from Moreno. While the Spaniard may have more pace and be more comfortably overlapping the wide forward, his defence is suspect and individual mistakes have blighted his Liverpool career. Could we really be confident in his ability to thwart Bolasie?

The contest to be Liverpool’s first-choice left-back is an ongoing battle that can never truly be won. At elite clubs with at least two options for every position, only consistency in performance can ensure your place is retained. Yet Robertson at least has his head above water again.

When Klopp spoke after signing him in July, it was revealing that he spoke of Robertson’s “outstanding attitude” as the primary motivator behind the move. “His talent and skills – also very, very good,” Klopp continued, but almost as an afterthought. The ‘90% mental and 10% physical’ cliche rings true once again.

Six weeks after his Liverpool future was being called into question, Robertson has demonstrated the professionalism and resolve that have long served him well. The social endorsement from Liverpool supporters after Friday’s FA Cup derby was resounding: ‘Finally we have a proper left-back’.

Daniel Storey