Cahill was an unused substitute in Millwall's overnight 2-1 win against lower-table Sheffield Wednesday, meaning the Socceroos great has played six minutes out of a possible 450 since joining the Lions.

It's an unsustainable trajectory, and one that creates headaches for van Marwijk, who will soon have to decide whether to call-up the 38-year-old for March friendlies against Colombia and Norway, or allow him to continue, supposedly, working his way into the Millwall team.

Once an almost-certainty, Cahill's chances of playing for the Socceroos under a new, short-term coach who, it's fair to expect will have little sentimentality for the Aussie legend, seem slim.

Van Marwijk's already singled out Tomi Juric as one of his must-scout players in Europe. Golgol Mebrahtu is back from injury and banging in the goals in the Czech Republic, while Jamie Maclaren's off the mark in Scotland and playing every game.

It was always going to be tough, going from a largely unused sub at Melbourne City, to a regular inclusion, let alone starter, at the mid-table Championship side. There are no rewards for experience in the Championship. 

Millwall currently sit eleventh in the league, a fantastic achievement for the newly-promoted club, but that doesn't necessarily mean Cahill's chances will increase as Millwall's safety becomes a certainty.

Despite the large financial considerations to a top-half finish, and the obvious board objectives, bonuses and contract-negotiations that rely on continued performances, Millwall's coach, Neil Harris, is entering his third year of professional management and has greatly impressed at the Den.

Much bigger, better-paying clubs will be interested in his services in the off-season. This is England after all, where the revolving door of managers never shuts. In other words, Harris has much more than a fairytale ending for Cahill on his mind. 

There are also practical considerations at play. Millwall play a classic 4-4-2 formation (of course they do) that leaves no central-attacking midfield role for Cahill. The Aussie striker has rarely excelled playing as part of a front two before, and Harris surely knows this. 

Then there's form. Lions' striker Lee Gregory has been in excellent form this season and Millwall are in no short supply of goals, with five regular goal-scorers this season. Meanwhile, second striker Steve Morison is club-captain and something of a Millwall legend himself.

Substitue striker Aiden O'Brien, meanwhile, has hit his stride at the worst possible time for Cahill. O'Brien can't get a regular spot in the side, but is prolific off the bench. 

Ultimately, it's hard to write Timmy off completely. Harris is Cahill's former teammate, and by all-accounts eager to have the Aussie in his side. He's been very encouraging about Cahill's chances.

But the Millwall coach can't hide what everyone knows to be correct. Cahill's almost missed an entire season, at 38-years-old, and is now trying to get into one of the world's toughest leagues.

In short, it's going to take a miracle. Hopefully Timmy's saved his best for last.