The trio were long-time teammates at Anfield.
Agger has called a premature end to his career
The Dane, who left Anfield two summers ago to return to his homeland with Brondby, posted on Twitter that although he's "proud" of his career, it's the "right decision" to stop.
Thank you for your support.A great experience.It's sad,but it is the right decision to stop. I'm proud of my career. pic.twitter.com/Geu9y47vnN— Daniel Agger (@DanielAgger) 9 June 2016
Agger, who arrived in Liverpool via his most recent employers in 2006, struggled with injuries during his time on Merseyside and only in one campaign did he appeared in more than 30 league matches.
The 75-cap international won the 2012 League Cup at Anfield, adding to the league and cup honours he won during his first spell as a Brondby player.
Despite this, Agger made a big impact on Merseyside, where he was popular with fans and teammates alike.
And two of those, his former defensive colleagues Jamie Carragher and John Arne Riise, were quick to pass on their best.
"Well done on a fine career after his retirement today. What a left foot!" Wrote Sky pundit Carragher, while the Norwegian posted: "Thank you for everything. Proud to have played with you. All the best mate".
Well done to @DanielAgger on a fine career after his retirement today. What a left foot!— Jamie Carragher (@Carra23) 9 June 2016
Thank you for everything @DanielAgger proud to have played with you. All the best mate— John Arne Riise (@JARiiseOfficial) June 9, 2016
Both players were at the club at the time of Agger's arrival, though Riise was sold to Roma in 2008 and Carragher retired the summer before the Dane's departure in 2014.
Liverpool also expressed gratitude to their former number 5, posting the words: "Thanks for the memories", alongside a selection of photographs showcasing the player's best moments at Anfield.
Carragher and Agger lead out the Reds