Robertson was expected to play second fiddle to Alberto Moreno at left-back - and that was very much the case for the first few months.
It was a difficult start to life on Merseyside for Robertson, who found himself being left out of matchday squads upon joining.
But Moreno’s errors gave Robertson an opportunity and it’s an opportunity he seized with both hands.
Robertson all-energy performances and passion soon saw him become a first-team regular as well as a fan favourite.
Years on and Robertson has arguably established himself as the best left-back in world football. He’s helped the club win the Champions League, the Club World Cup and their first ever Premier League title.
He will go down as a club legend.
But it’s just for the level of his performances.
Robertson has become a cult hero at Anfield due to his sh*thouse behaviour.
And to celebrate the anniversary of him joining Liverpool, we’ve decided to remember the greatest sh*thouse moments in the last four years.
Battle vs Rafinha in the Club World Cup
After Sao Paulo’s Rafinha crunched into Sadio Mane just before half-time, Robertson assured his teammate that he’ll “get him back.”
Seven minutes into the second half, Robertson did just that.
Then, after Liverpool’s victory in extra-time, Robertson gave his opponent some verbals.
Elbowing Tom Davies and then laughing in his face
After Tom Davies put in a strong tackle on Robertson, the left-back made sure he landed on the Everton midfielder with his elbow - it didn’t go down too well which left Robertson simply laughing in his face.
Pushing Kyle Walker and then laughing in his face
Robertson loves a little nudge into the back of an opponent to send them into the crowd. During a 3-1 victory over Manchester City, he did just that at Anfield before walking off and laughing at the right-back.
The Liverpool fans loved it and started chanting “Ooooh Andy Robbo.”
Making Ayoze Perez lose his head
After a late James Milner penalty beat Leicester 2-1 at Anfield, Robertson decided to push Ayoze Perez at full-time during his celebrations.
It left Perez fuming as a pushing match between the two sides broke out.
Shoving Lionel Messi in the head
Robertson and needless shoves - name a better combination.
The Scot set the tone for an incredible semi-final comeback at Anfield by rattling Lionel Messi inside the first few minutes. Liverpool had trailed 3-0 from the first-leg but with Robertson in his best sh*thouse form and running around like a madman, the Reds produced an incredible 4-0 victory.
Mocking Luis Suarez after Liverpool 4-0 Barcelona
Robertson was actually forced off with an injury at half-time of that incredible night. Luis Suarez had purposely tripped him, which caused the injury.
But Robertson had the last laugh.
In a post-match interview, Des Kelly said to Robertson: "You had a running battle with Luis Suarez and he took you out."
Robertson replied with: "Who's going to the final?”
One thing we’ve learned is that Robertson isn’t scared on fighting the best players in the world.
During a 2-1 defeat to Paris Saint-Germain, he had enough of Neymar and took out his anger with a brutal challenge.
Unsurprisingly, it left Neymar rolling around on the turf.
After the match, Robertson said:
“I suppose they were in the lead and they were looking to waste time. You can use gamesmanship, play-acting, you can use it all really.
“I would like to know how much time they wasted tonight. It’s frustrating when [Neymar] is falling like he is.”
Celebrating Dundee United’s win against Dundee
Robertson only played for Dundee United for one season but he hasn’t forgotten his shoots.
After a penalty shootout win against rivals Dundee, Robertson celebrated it with a simple tweet saying: “See nothing has changed.”
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