It's asserted by Chinese sources that Postecoglou - who was first linked with a big money approach from the CSL in February - asked FFA CEO David Gallop to be released from his contract after September's 2-1 World Cup win over Thailand to take up the offer.
However, with qualification for Russia still on the line as the Socceroos finished adrift of Japan and Saudi Arabia in their group, Gallop persuaded Postecoglou to retract his request for an early release from a contract which covers the current World Cup cycle.
Such was the determination of the FFA to keep Postecoglou at such a critical period that they added the further deterrent of compensation from Shenhua.
Desperate to try his hand again at overseas club management, the recent cascade of criticism over his tactics and team selections, and a strained relationship with the FFA hierarchy, has only hardened Postecoglou's resolve to turn the China approach into a concrete deal.
It appears to be the final piece of jigsaw explaining the revelations after Tuesday's win over Syria that he will leave after next month's final World Cup qualification showdown against Honduras - no matter what.
The 52-year-old is thought to view the CSL as the perfect fresh start with one of Asia's best financed and biggest spending clubs.
Shenhua chairman Wu Xiaohui is said to view Postecoglou - highly respected in China after bringing Asian Cup glory to Australia in 2015 - as the man to lift the club's fortunes.
Shenhua are currently home to $1 million-a-week Argentine flop Carlos Tevez, who has scored just three goals in 13 CSL appearances and has been ridiculed by the club's fans.
Tim Cahill managed 11 in 28 games in his short spell there.
There is a sense of urgency for Postecoglou to lock down the job, according to the China sources, in the knowledge the club may look elsewhere should the deal not be finalised soon.
Postecoglou's impending Socceroos exit has yet to be officially confirmed or denied by either himself or FFA.
With Gallop on Monday reiterating only that Postecoglou is only focused on the November qualifiers.
"Obviously I've spoken to Ange a number of times, a number of factors go into this kind of thing," Gallop said.
"He's made no secret of the fact he wants to coach week-in week-out again (at club level), but his focus is on November and knuckling down to the task which is to qualify for our fourth consecutive World Cup."
As things stand, he will remain until after next month's intercontinental World Cup qualification play-off against the Central Americans.
In the interim, Shanghai - who sit a disappointing 11th on the CSL ladder with four league games to go - have installed technical director Wu Jingui as Uruguayan Poyet's short-term successor.
A silver lining from a dire season could come in the form of the CFA Cup, with Shenhua to face local rivals Shanghai SIPG in the final on November 18.