Tim Cahill played 13 minutes for Millwall as Fulham moved up to second place in the Championship table courtesy of an impressive 3-0 away win on Friday.
The 38-year-old came on in the 77th minute for fellow Socceroo James Meredith with his team behind by two goals.
Slavisa Jokanovic's side extended their unbeaten league run to 22 games as they leapfrogged over Cardiff City to boost their hopes of automatic promotion to the Premier League.
However, they had to come through an early onslaught from Millwall, who remain in the play-off places despite seeing a 17-match unbeaten run in the Championship come to an end.
Fulham goalkeeper Marcus Bettinelli tipped Jake Cooper's firm header onto the bar before George Saville saw a goal chalked off due to a foul.
Yet the hosts were caught cold in the opening minute of the second half, Ryan Sessegnon pouncing on a loose ball after keeper Jordan Archer found Aleksandar Mitrovic's low drive too hot to handle.
Kevin McDonald doubled the lead with a long-range strike in the 56th minute, with the impressive Mitrovic rounding out the scoring in the closing stages, the on-loan Newcastle United forward providing the finish to cap substitute Tomas Kalas' break.
The result sees Fulham not only do the league double over Millwall but also go two points clear of nearest rivals Cardiff, albeit the Welsh club do have two games in hand.