Lucas Leiva wished the Dane good luck ahead of his move back to Brondby on Twitter.
The Denmark defender's Anfield departure was confirmed yesterday, as the 29-year-old ended an eight-year stay on Merseyside.
Agger had won the FA Cup and reached the Champions League final with the Reds, scoring in the semi-final of the competition in 2007 to help get Rafa Benitez's side to Athens (where they lost to AC Milan).
Since Brendan Rodgers was appointed Liverpool boss, though, the centre-back fell out of favour and dropped down the pecking order, below the likes of Dejan Lovren, Martin Skrtel and Mamadou Sakho.
As such, a move back to Brondby appears to make sense - but Lucas is nevertheless sad to see him go.
A more pressing matter for the Brazilian, though, is his own future, with Lucas said to be close to a move to Italian side Napoli.
According to reports, the 27-year-old could be set to reunite with former boss Benitez in Serie A, though a deal has now been left until deadline day.
Lucas has already appeared emotional over Instagram, reflecting on his European debut in a manner that could be interpreted as rueful.
And with Agger now having left the club, as well as Rodgers' warning that his fringe players must leave or risk getting limited game time, the Brazilian could be on his way out.
But the midfielder is not going to Aston Villa or Southampton, that's for sure...
@indykaila so you giving wrong information to your followers.— Lucas Leiva (@LucasLeiva87) August 31, 2014
Lucas started Liverpool's Premier League opener against Southampton but was substituted after a poor performance - and was then left out of his side's squads against Manchester City and Tottenham.