Wrexham were denied a dramatic goal in extra-time by VAR with Alejandro Garnacho and Joao Pedro securing an unconvincing 4-2 win to book Chelsea's place in the FA Cup quarter-finals.
Lewis Brunt sent the Racecourse Ground into raptures when he latched onto Kieffer Moore's flicked header from a corner and tapped home to make it 3-3 on the evening in the 114th minute, only for replays to cut the historic celebrations short due to an offside.
Deep into added time of extra-time, substitute Joao Pedro raced forward to net a fourth after Garnacho had earlier put the Premier League giants ahead for the first time in the tie in the 96th minute, securing Chelsea's place in the next round despite a lacklustre performance.
Liam Rosenior's side - who made nine changes and looked disjointed throughout - were forced to come from behind on two occasions to beat their Championship opponents in a game where the magic of the Cup and the threat of a Hollywood script-style ending loomed large throughout.
Sam Smith sparked those dreams with his well-taken opener but after slotting the ball past Robert Sanchez, the bubbling atmosphere was quickly burst when George Thomason's clearance to deny Garncaho cannoned off Arthur Okonkwo to draw Chelsea level.
A spirited performance from the hosts continued and Wrexham capitalised on that momentum when they retook the lead through Callum Doyle with 12 minutes of normal time to go.
A neat flick from the defender - who teed up Smith for the opener - diverted Josh Windass' strike in and sparked wild celebrations. But Chelsea found another reaction through unlikely candidate Josh Acheampong, who danced into the box and crashed another equaliser in at the near post four minutes later.
A red card for George Dobson to reduce Wrexham to 10-men in the 93rd minute added to an eventful first encounter with VAR, with the game only slipping away from their grasp once the decision was reviewed and upgraded from an initial yellow card.
"I thought VAR was meant to be for clear and obvious decisions. Dobbo's gone in with force. The referee is in a good position to see it. He has scraped his shin," Wrexham boss Phil Parkinson told TNT Sports.
"It's caught him low down. I thought he could've easily kept that as a yellow. In my opinion, I don't think the VAR should've intervened.
"It was a tight call and if that's the case you should leave it with the on-field decision."
Despite feeling aggrieved at the decision and the implications that unfolded, Wrexham can be proud of their performance.
Co-owners Rob Mac and Ryan Reynolds applauded their side at the final whistle and left to reflect what could have been on a night which had threatened to provide another fairy tale ending.
Chelsea boss Liam Rosenior speaking to TNT Sport:
"We're through. It wasn't the best performance. A really, really difficult game.
"You have to give your players opportunities. You have to see your squad and manage your squad.
"This team played the most games than any other club over the last 18 months in world football. It's crazy to just keep going and risk player injuries when we want to achieve what we want to achieve.
"Some of the elements of our play was very good, and we are through to the next round."
Wrexham boss Phil Parkinson speaking to TNT Sport:
"There were so many elements of our play to be pleased with. Our pressing, our discipline, but also some of the football we played. We carried a threat tonight which we thought we would.
"We didn't come here tonight just to stop Chelsea. It's such a shame that our first taste of VAR has gone this way because it will be the talking point."
