Steve McManaman has told Liverpool the days of them being able to hand-pick their next manager were "long gone".
Former Anfield hero McManaman suggested anyone who thought the likes of Pep Guardiola or Jose Mourinho would be interested in replacing the sacked Kenny Dalglish was not "living in the real world".
Some say Liverpool's status as one of the most successful clubs in European history should allow them to get almost anyone. But McManaman said: "That's not the case any more. You can't identify Pep Guardiola and go and get him, you can't identify Jose Mourinho and go and get him. Those days of that type of appointment have long gone."
Liverpool's owners, Fenway Sports Group, have been criticised for a recruitment process that has already seen them snubbed by Swansea boss Brendan Rodgers, amid reports they would attempt to interview up to 12 candidates.
The Reds have been given permission to speak to Wigan's Roberto Martinez, while it has been suggested they also want to meet former Chelsea manager Andre Villas-Boas and are even considering reappointing Rafael Benitez, both of whom are currently out of work.
McManaman added: "It's unrealistic, isn't it? Of course, we'd like Pep or we'd like Jose Mourinho - but we're living in the real world. I don't know who's available, who's willing to come. The finance is a big thing, whether you're going to have to extricate someone from a contract. It's not like it was 20 years ago."
McManaman refused to criticise FSG's approach to finding a new manager and defended their attempts to interview Rodgers and Martinez, among others.
"I know they're speaking to a number of managers, aren't they, and trying to bring in the right appointment," he said. "I presume that's all you can do. They've also spoken to a lot of high-calibre managers. It's just that we don't know about them.
"People are picking on Roberto Martinez and Brendan Rodgers. They're both wonderful managers and Roberto Martinez is a superstar - he's a friend of mine."
Dalglish lost his job on Wednesday following Liverpool's worst Barclays Premier League finish - eighth place - for 18 years and their lowest points tally - 52 - since 1954.