It seemed Championship strugglers Millwall were on the brink of delighting their home crowd at the Den at 2-0 up with just two minutes of normal time left after second-half goals by Alex Pearce and Aiden O’Brien.
But Brighton pulled one back through Jurgen Locadia and then, in the fifth minute of added on time and the last act of regulation play, Solly March’s seemingly harmless free-kick into the box left Millwall goalkeeper David Martin flapping at the ball before it settled in the top corner to give the Seagulls an unlikely equaliser.
Premier League Brighton, beaten FA Cup finalists in 1983, had the best chance of a lacklustre first half, with Beram Kayal volleying straight at Martin.
South London side Millwall, defeated in the 2004 FA Cup final by Manchester United — Brighton’s conquerors in 1983 — had the better of much of the second half, however, and they were rewarded with two goals in nine minutes that left them on course to make the journey across the capital to Wembley.
The deadlock was broken in the 70th minute when Pearce headed in at the back post, the goal standing despite Brighton’s Glenn Murray seemingly being fouled in the box.
Millwall then doubled their lead when O’Brien nodded in a Jed Wallace cross.
Brighton substitute Locadia’s left-footed shot on the turn appeared to be no more than a consolation goal before March broke Millwall hearts.
Millwall were reduced to 10 men a minute from the end of extra time when Shane Ferguson, a possible penalty-taker, was sent off for a stamp on Lewis Dunk.
At the very end of extra time, Brighton thought they had a winner only for Martin Montoya, in a match without VAR, to be incorrectly flagged for offside as the tie headed to spot-kicks.
Further drama followed when Murray struck the opening penalty of the shoot-out onto the crossbar.
Both sides then found the back of the net until Ryan blocked Mahlon Romeo’s effort with his legs to leave the shoot-out level at 3-3 before ‘sudden death’ came into play at 4-4.
Brighton skipper Dunk then powered a penalty low to Martin’s right before, with Millwall needing to score to keep the tie alive, Jake Cooper saw his shot clear the goal.
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