Eden Hazard fired Chelsea into an all-English Europa League final against Arsenal with perhaps his last-ever kick at Stamford Bridge.
The Belgian forward dispatched the decisive penalty as Chelsea edged out Eintracht Frankfurt 4-3 in a shoot-out that followed a 1-1 draw in west London.
Kepa Arrizabalaga produced two fine saves to spare Cesar Azpilicueta's blushes, as the Blues captain missed his own spot-kick.
Kepa saved Martin Hinteregger's penalty with his knees before palming away a good effort from Gonzalo Pacienca as the Blues set up a showdown with London rivals Arsenal in Baku, Azerbaijan, on May 29.
Should Hazard's reported big-money transfer to Real Madrid materialise this summer, the 28-year-old will have capped his Stamford Bridge tenure in the most dramatic of fashions.
Spanish stopper Kepa joined Hazard in the hero's corner, and that after proving the villain of Chelsea's shoot-out loss to Manchester City in the Carabao Cup final back in February.
From refusing to be replaced that day as Chelsea lost 4-3 to City on spot-kicks, now Kepa is the toast of west London following two fine penalty saves.
Ruben Loftus-Cheek's fine goal had initially put Chelsea in control, only for Luka Jovic to tuck away his 10th goal of the Europa League campaign.
Hazard conjured up an impetuous assist for Loftus-Cheek's 10th goal of the season, but Eintracht forced the game into extra time - with the scores 1-1 on the night, 2-2 on aggregate and level on away goals.
A microcosm of Chelsea's season and Maurizio Sarri's tetchy Stamford Bridge reign in a single contest, the Blues bossed the first half only to tumble from that perch after the break.
As Sarri's regimented game plan stuttered and his disorganised players stumbled the taskmaster Italian stalked the touchline in frustration, ignoring the fourth official's constant demands to stay inside his technical area.
Sarri snubbed Gary Cahill for perhaps the final time, leaving the former England defender on the bench when Andreas Christensen hobbled out injured.
Where Sarri could have replaced Christensen directly with the ever-reliable Cahill, instead he turned to full-back Davide Zappacosta.
That meant a full defensive reshuffle, with Azpilicueta moving into central defence.
The already frustrated home fans had no patience left then when Sarri withdrew clear man of the match Loftus-Cheek for Ross Barkley with extra time looming.
The deafening boos were just the latest instalment of the Chelsea fans voicing their catalogue of frustrations with the former Napoli manager.
Chelsea's present talisman fed a potential future great as the Blues took control midway through the first half. Hazard's angled pass on the spin bisected Eintracht's defence, but Loftus-Cheek's run and finish matched the Belgian's majesty.
Frankfurt dangerman Jovic headed straight at Kepa early on, but Chelsea dominated the opening half and fully merited Loftus-Cheek's eye-catching goal.
The Blues were denied a penalty when Danny Da Costa barged over Loftus-Cheek after Olivier Giroud had missed Willian's near-post cross.
Chelsea paid for a tentative second-half start when Jovic strolled through a poorly aligned home defensive line to equalise and put the tie right back in the balance.
The visitors had hardly stopped appealing for a penalty handball when Jovic cantered clear, with David Luiz stranded too high out of the line and Emerson playing him on.
The arch Serbian finisher made no mistake with the easy chance, leaving a stunned Chelsea back to square one.
Every time Chelsea wasted a half-chance or passed away possession, Frankfurt grew in stature and confidence.
Christensen hobbled out for Zappacosta, and then Azpilicueta was merely booked for that rash scything challenge.
The Blues' panic had Sarri almost sent to the stands, with the fourth official nearly losing patience with the Chelsea manager's touchline wandering.
And then the under-fire Stamford Bridge chief withdrew Loftus-Cheek, the star of the show.
Azpilicueta again swerved dismissal despite a cynical handball, with the officials simply awarding a free-kick.
Hazard and replacement Gonzalo Higuain botched a big chance on a counter-attack to launch the added 30 minutes.
Then Sebastien Haller bungled a gilt-edged Eintracht opportunity, mishitting his shot to allow Luiz a full-stretch clearance off the line.
Zappacosta headed off the line from Haller to close the first period of extra time. Azpilicueta thought he had won it when bundling the ball across the line, only for the goal to be chalked off for a foul on Eintracht keeper Kevin Trapp.
When the game slipped into the lottery of penalties, however, Hazard saved Chelsea once again.