Wycombe were seconds away from victory as they lead 1-0 in extra-time after Southend goalkeeper Daniel Bentley’s own goal following an expert Joe Jacobson free-kick but Joe Pigott forced a penalty shootout with a 120th minute equaliser.
Bentley then became the hero in the shootout when he palmed a Sam Wood effort onto the post.
Sam Saunders will struggle to forget the opening five seconds of the game after he suffered a game ending injury when he tweaked his calf receiving the ball from the kick-off under pressure from Will Atinkson.
He was nearly in tears as he hobbled off to be replaced by Matt Bloomfield – as Wycombe made the fastest substitution in play-off history.
Wycombe struggled to deal with the loss of their key midfielder and could count themselves slightly fortunate not to be behind after 14 minutes when Cian Bolger flicked a header wide from a brilliant Atkinson corner.
Southend continued to threaten with balls into the Wycombe box and Barry Corr had an effort disallowed on 22 minutes.
Corr leapt highest to head home a David Worral free-kick but the referee had already blown for a foul by Cian Bolger on Nico Yennaris.
The game struggled to find a consistent tempo and quality in the final third was in short supply with defenders outwitting attackers but it sparked into life on 69 minutes.
Corr went down in the box under what looked shove by Jacobson. It looked identical to the foul given on Yennaris earlier in the game but the referee was unmoved and waved away passionate penalty appeals by all the Southend players.
Paul Hayes forced Bentley into a smart save when he found space down the right-hand side of the box but the sides couldn’t be separated and extra-time was needed.
Quality had been in short supply in a cagey affair – that was until a moment of magic from Jacobson handed Wycombe the lead.
He curled a fantastic 25-yard free-kick that hit the underside of the bar before deflecting off Bentley’s back and into the net via the crossbar again.
Wycombe had chances to sew the game up in the second-half of extra-time as Aaron Holloway raced through on goal but fluffed his lines.
Southend looked down and out, and even a few hundred fans gave up the ghost, flocking out of Wembley as the fourth official added two minutes of added time.
However, those fans that left missed one of the most dramatic goals in play-off history as substitute Piggot latched onto a Corr knockdown and was coolness personified as he fired into the bottom corner from 15 yards.
Momentum was now with Southend in the shootout but Ben Coker handed the advantage back to Wycombe with a poor penalty straight down the throat of goalkeeper Alex Lynch.
Wycombe again had League One in sight but Bloomfield was denied by a fantastic save Bentley to draw the teams level.
Despite the sudden death nature of the shootout both sets of penalty takers kept their cool with some fantastically took spot-kicks and it was only a brilliant save from Bentley to divert Wood’s penalty off the post that separated the teams.
The drama of the play-offs once again delivered with spectacular results.