Cahill came to prominence at the unfashionable team from southeast London, firing them into the 2003-04 FA Cup final before leaving for Everton.
Now with New York Red Bulls, the 34-year-old has been linked with the likes of Queens Park Rangers and Sunderland, as well as Sydney FC.
A loan move away from Red Bull Arena could be a possibility during the Major League Soccer close season and Championship side Millwall have expressed their interest.
"I would sign Tim Cahill all day long but I don't want to lift our fans' hopes only for them to be let down," Millwall manager Ian Holloway was quoted as saying by the Southwark News.
"I wouldn't want to put Tim in an awkward position where he would have to turn down Millwall - that wouldn't be fair.
"We all know he loves the club and that he's a fantastic player.
"If I had a chance to speak with Tim, I'd tell him that we'd love to have him back but I would hate to make a legend choose someone else over us.
"It would be similar to the chat I had with Bobby Zamora - I would see if our needs and Tim's needs married up.
"Is it possible? Should we be doing it? That's the kind of conversation it would be.
"Hopefully we can have a chat but in the meantime I want to make some of our young players as famous and legendary as Tim Cahill is."
Cahill's likely participation for Australia in the 2015 Asian Cup on home soil could well prove a barrier to a European loan move.
However, Millwall CEO Andy Ambler believes it is incumbent on the club to try and make a surprise second spell at The Den a reality.
"We'd love to talk to Tim about that," he said.
"If he turned around and said 'thanks but no thanks', we'd have to respect that but we would be mad not to ask the question.
"Every club would want someone of his quality at their club - but never say never. We would love it to happen.
"We would love to talk to Tim and his representatives but we recognise there will be huge interest in him."
Now with New York Red Bulls, the 34-year-old has been linked with the likes of Queens Park Rangers and Sunderland, as well as Sydney FC.
A loan move away from Red Bull Arena could be a possibility during the Major League Soccer close season and Championship side Millwall have expressed their interest.
"I would sign Tim Cahill all day long but I don't want to lift our fans' hopes only for them to be let down," Millwall manager Ian Holloway was quoted as saying by the Southwark News.
"I wouldn't want to put Tim in an awkward position where he would have to turn down Millwall - that wouldn't be fair.
"We all know he loves the club and that he's a fantastic player.
"If I had a chance to speak with Tim, I'd tell him that we'd love to have him back but I would hate to make a legend choose someone else over us.
"It would be similar to the chat I had with Bobby Zamora - I would see if our needs and Tim's needs married up.
"Is it possible? Should we be doing it? That's the kind of conversation it would be.
"Hopefully we can have a chat but in the meantime I want to make some of our young players as famous and legendary as Tim Cahill is."
Cahill's likely participation for Australia in the 2015 Asian Cup on home soil could well prove a barrier to a European loan move.
However, Millwall CEO Andy Ambler believes it is incumbent on the club to try and make a surprise second spell at The Den a reality.
"We'd love to talk to Tim about that," he said.
"If he turned around and said 'thanks but no thanks', we'd have to respect that but we would be mad not to ask the question.
"Every club would want someone of his quality at their club - but never say never. We would love it to happen.
"We would love to talk to Tim and his representatives but we recognise there will be huge interest in him."