Liverpool great Kenny Dalglish has said he was surprised by Jamie Carragher's decision to retire at the end of this season.
Carragher, 35, announced on Thursday that he would call time on an Anfield first-team career that stretches back to January 1997.
Dalglish, who was the defender's Liverpool manager for an 18-month spell from the beginning of 2011, feels he still has more to offer as a player.
Carragher started only one Premier League game before Christmas this season but has become a regular again of late, starting each of the club's last three matches.
His performances during the recent 2-2 draws at Arsenal and Manchester City had led to suggestions that current manager Brendan Rodgers might offer him a new deal.
"Jamie's decision was a surprise to me, because he has just played as well as anyone against Arsenal and Manchester City," Dalglish told the Liverpool Echo.
"But he knows himself better than anybody and, if he thinks it is time to hang up the old boots, that is totally his prerogative. It is always a difficult decision for a footballer - as hard a decision as you can face as a professional.
"It is more difficult because playing is the best part of your career, especially at the level he has played at and is playing at. That makes it so much more difficult to retire. But it's Jamie's shout, his call.
"I'm just surprised. I thought he had a bit left in him yet."
Dalglish was the Liverpool manager when Carragher first arrived at the club as a nine-year-old in 1987.
"I remember him well in those days as a centre-forward," he said. "They used to train at Netherton, and my own son Paul was there at the time.
"I also remember him scoring on his Anfield debut in 1997, which was obviously a very special moment for him.
"I am not sure if he has any ideas about what he wants to do next, but I am sure the door at Liverpool Football Club will always be open to him."
Fellow former Liverpool boss Rafa Benitez also praised Carragher, describing him as "one of the best centre-backs" of his era.
Benitez was Carragher's manager for six years at Anfield between 2004 and 2010, and the player has credited the Spanish coach with turning him into a much better defender.
"To play more than 700 games for any team in football is a really, really great achievement," Benitez said. "More than 700 games for just one club is even better so no one can argue about his character, determination and professionalism.
"Carra was a key player for us. In 2007, John Terry - who is a very good centre-back - he said Carra was one of the best centre-backs at that time. We were really pleased in terms of watching him, training every day, hard worker, and playing every game."