The defender joined the Reds on loan from Queens Park Rangers in January 2016, but made just three appearances for Jurgen Klopp’s side and was used as a makeshift striker before spending the remainder of the season representing the club’s under-23s.

His first three appearances for the Reds were as a late emergency striker, setting up a 95th-minute winner for Adam Lallana at Norwich City. He then played the full 90 minutes of the FA Cup fourth-round tie against West Ham, and apart from two occasions as an unused substitute, he never featured again.

Caulker, who celebrates his 32nd birthday today, would go on to play for Dundee, Alanyaspor, Fenerbahce, Gaziantep, Fatih Karagumruk, Wigan Athletic before joining Malaga City Academy as player-manager earlier this month.

But speaking to the Guardian back in April 2017, Caulker bravely revealed how his Liverpool career was cut short after he was forced to enter rehab. The former Tottenham Hotspur man detailed how he was admitted into rehab after a string of drunk and disorderly offences and also told of how he has battled with depression for much of his career.

He said: “I’ve sat here for years hating myself and never understood why I couldn’t just be like everyone else. This year was almost the end. I felt for large periods there was no light at the end of the tunnel.”

Before he added: “Sometimes I’d be sat there with the police and my lawyer, watching the CCTV footage of what I’d done, and I didn’t recognise myself.

“I couldn’t believe the person I was. It’s so hard to accept I could be like that. In Liverpool, I was waking up in the middle of the night, throwing up. People were blackmailing me, club owners, and bouncers: ‘Pay money or we’ll sell this story on you.’

“And I had no idea what I’d even done on those blackouts. I eventually told the club I could not function and needed to go back into rehab.”

In a separate interview with FourFourTwo in the same year, Caulker revealed: “I was really low. The cycle of gambling, drinking, and self-loathing was supposed to numb the pain, but it only made things worse.

“At the time, I thought I was at rock bottom. I was wrong. After a couple of months, I knocked on Jurgen Klopp’s door and said, “I don’t feel like I’m good enough – what do I need to do to improve?

“He gave me some suggestions for the gym, but I was mostly playing for the under-23s, and that rejection was difficult to handle.

“In a dark place, I didn’t feel like I could train and fulfil my duties, so I decided it was time for rehab. That was extremely hard, because I’d been given such a massive opportunity at Liverpool.”

Speaking on the Under The Cosh podcast earlier this year, Caulker admitted that he wasn’t sure if he was ‘even sober’ when making his debut for the club against Arsenal.

“Monday I signed, Tuesday I trained and then Wednesday was the game,” he revealed. “I was sh***** myself and thought, ‘I’m gonna start here’ because they had seven centre-halves out injured.

“And I was thinking, ‘Oh my god, I’m going to start. Am I even sober? How the f*** am I going to do this?’ I was panicking. That train journey up, I was panicking because I hadn’t been taking care of myself, I was a mess. I was worried.

‘I don’t know who played centre-half, I can’t remember, but [Klopp] put someone else in [Toure and Sakho]. He said to me, ‘Come get warm’, but we were losing 3-2. He said, ‘No, you’re coming on. I’m going to put you up front’.

“I was like, ‘What’. I didn’t get time to ask him and we ended up getting the equaliser and after the game he just came over high-fiving me [and saying] that, ‘They all think you’re crazy until it works’.

“It’s true. I was just sat there in the changing room for ages thinking what has just happened. My dad was there to see it as well, a beautiful moment and that’s special. No one can take that from you.”

Caulker also claimed on the podcast that he was not fairly treated during his loan spell at Anfield. He believes Klopp formed a false impression of him after declaring himself unavailable to participate against West Ham United in an FA Cup tie.

He said: “Things did change for two months. I’ve gone there; it’s the chance of a lifetime. I was white-knuckling it.

“I didn’t know how to deal with my addiction (drink/gambling); I was somehow dealing with it because I wanted the opportunity. But the opportunity never came. I had a couple of run-outs up front, played one game as centre-halve, did alright, against West Ham.

“We then had the cup replay against West Ham and I’d done my back in; horrible spasms; I couldn’t get rid of it. The morning of the game, I’ve had to tell him I can’t play. I was due to start, but I said I actually can’t play.

“I was devastated, and from that moment on, he wrote me off. I think he wrote me off as one of those guys who didn’t want to play or who was scared to play. It couldn’t have been further from the truth.

“That was it; my moment was gone. As soon as that went, and I felt it go because then he started putting me in the U23s to play every week, I was like, ‘Nah, that’s not on.’ You see it all the time; the manager just goes, ‘You’re not for me; out you go; get down with the kids.'”