Tim Cahill showed just what might have been for Millwall as he shrugged off a seven-month lay-off to settle this stirring derby.
The two teams respective league positions meant little hinged on this encounter other than points and pride. But the small mater of South London superiority and the quest to finish above your nearest and bitterest rivals meant this game had an end of season edge.
Mark McGhee's Millwall, started the brighter intent on avenging their 1-0 defeat at Selhurst park in December.
And they should have been ahead as Paul Ifill found space on the right, but with Neil Harris better placed, the Lions winger blasted wastefully over.
Having survived the opening onslaught Palace came back strongly as Steve Thomson forced Tony Warner to tip over, while Shaun Derry's free-kick just clipped the wall to send it to safety.
Andy Roberts was on hand to block Tommy Black's effort, but the Eagles were grateful to Lions centre back Darren Ward who merely guided a header into Dougie Freedman's path, and the strikers cut back and shot gave the visitors a 22 minute lead.
There was a touch of good fortune surrounding the Lions leveller as Ifill appeared to got his header away before Aleksandrs Kolinko collided with him. But referee Phil Prosser pointed to the spot and the Lions seized the initiative as Neil Harris stroked home the penalty.
Within minutes of equalising Millwall were ahead when Mark McCammon met Dennis Wise's cross at the near post.
And the striker should have added to his tally on the stroke of half time, but failed to connect with Ifill's cross when only six yards out.
The Lions paid dearly for that miss three minutes after the restart as Black's driven cross was turned into his own net by Roberts.
The stirring contest continued with Harris denied a clear penalty while Roberts cleared from the line at the other end.
But the day was made for Cahill who marked his return to first team duties at the Den after his cruciate ligament injury as a second half substitute, and it was the Australian midfielder's trade mark header from another Wise corner that sent the Lions fans home happy.