The 23-year-old played his first senior game since last September in Liverpool’s 1-0 friendly win at neighbours Tranmere on Saturday, as he battles to re-establish himself in the Anfield club’s defence.
Agger cost £5.8million (€7.2m) from Brondby in January 2006, and made a massive impact at Liverpool, ousting veteran defender Sami Hyypia from the side to become Jamie Carragher’s new defensive partner.
A serious metatarsal injury just a handful of games into last season sidelined him – but the young Dane successfully completed 75 minutes at Prenton Park in his comeback.
Liverpool fielded a side of youngsters and squad players in the match, with Yossi Benayoun’s first-half strike enough for a comfortable victory.
Agger will continue to work his way back to full match fitness at Liverpool’s Swiss training camp over the next fortnight with games against Lucerne, Wisla Krakow and Hertha Berlin in seven days.
He said: “I am delighted to be back, this has been the most frustrating time of my career, I have just had to look forward, concentrate, and work hard to get myself back to fitness.
“This season ahead is now all-important to me. I have missed so much football over the past year that I feel I am almost starting my career at Liverpool all over again.
“Now I am really focused on this season, I am ready. I have been working hard right through the summer to get myself fit for this level of football.
“It has been important to get myself ready so I can be available for the first day of the season.”
Liverpool boss Rafael Benitez has highlighted Agger’s absence last season as one of the key reasons their title challenge fell away.
“It has been so frustrating,’’ Agger admitted. ‘‘But I have been focused on getting back as soon as possible. That has been the most important thing. I have had to forget about the past and what has happened and keep looking forward. Everybody has been helping me. But I know myself, I know my body, and it has been down to me to get myself right.
“I have had a really strong will to get back, that is what I have been aiming for and it was great to get that first run-out at Tranmere in our first pre-season friendly. I have missed a lot, but there is such a lot more to come for me here.
“Since I was injured the club have bought Martin Skrtel, he’s a very good player, but that is what you expect at a club like this. There is always competition. I will fight for my place and I am sure that the other centre-halves here will do just the same.”
Benitez is still hoping to complete the Gareth Barry deal soon – Liverpool’s chief executive Rick Parry has had direct talks with Aston Villa’s American owner Randy Learner.
Significantly, Republic of Ireland defender Steve Finnan did not figure in the squad at Tranmere and could be used as part of the deal, despite Villa boss Martin O’Neill saying Liverpool have yet to improve their £15m (€18.7m) offer.
Benitez is steadily raising cash for his targets, which include Spurs and Republic of Ireland skipper Robbie Keane. Peter Crouch (€13.7m) and Danny Guthrie (€2.8m) were sold last week while Blackburn are trailing Jermaine Pennant, who played 45 minutes at Tranmere and would cost around £6m (€7.5m).
A similar fee would get Scott Carson, who is interesting West Brom and Stoke — with Benitez not wanting the goalkeeper to go out on loan again.
Liverpool gave debuts to new boys Philipp Degen and goalkeeper Diego Cavalieri, while last season’s back-up keeper, Charles Itandje, is lined-up for a £3m (€3.7m) move to Galatasaray.
Ex-Cork City midfielder George O’Callaghan started for Ronnie Moore’s side in a three man midfield, and played 80 minutes in his debut, though he struggled to stay the pace, according to the Tranmere boss.
“I thought George looked off the pace a little,” said Moore.
“It’s different playing at Cork than it is here against Liverpool. But he’ll get fitter and he’s going to be a good player for us.”