Millwall midfielder Jimmy Abdou stunned a partisan full house at Elland Road to send the Londoners through to the Coca-Cola League One play-off final following a 1-1 draw (2-1 on aggregate).
The Frenchman turned home substitute Lewis Grabban's cross in the 73rd minute to silence most in the biggest crowd outside the top flight this season.
Leeds striker Luciano Becchio had bundled home a 52nd-minute equaliser to level the tie and send most of the 37,036 attendance into delirium.
Jermaine Beckford, Leeds 34-goal forward, saw a 48th-minute penalty saved, before Argentinian team-mate Becchio appeared to have sent a nerve-jangling second leg towards extra-time.
But Abdou popped up to convert Millwall's only chance of the match and the Londoners edged through to their first play-off final at the fourth attempt.
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