Manchester United were dumped out of the FA Cup by Middlesbrough on penalties to prolong their near five-year trophy drought.
Anthony Elanga was the only man to miss in a mammoth shoot-out, with a total of 16 spot-kicks being taken.
Cristiano Ronaldo dragged an early penalty wide before Jadon Sancho gave United the lead after 25 minutes, with Ralf Rangnick's side showing they meant business in a competition of great importance to them.
But the Red Devils were left stunned when Matt Crooks' equaliser stood after a VAR check, despite Boro substitute Duncan Watmore clearly controlling the ball with his hand.
The game then lurched into extra-time, with Elanga missing the fatal penalty which put Chris Wilder and co in the hat for the fifth round.
Here are six talking points from Old Trafford.
Join the debate! What should Rangnick change at Man Utd? Give us your verdict here.
1. Munich respects paid
With February 6 on the horizon, Friday's match gave everyone inside Old Trafford the opportunity to pay tribute to those who tragically died in the Munich Air Disaster.
Sunday marks 64 years since the United team of 1958, famously known as the Busby Babes, were returning from a successful European Cup quarter-final against Red Star Belgrade via Munich airport.
Many of Matt Busby's side were killed after their aeroplane crashed on its third take-off attempt, along with supporters and journalists to make a total of 23 casualties.
As ever, United marked the occasion by both managers laying wreaths before kick-off and the players donning black armbands.
The Old Trafford faithful also held the icon 'We'll Never Die' tifo over the Stratford End, demonstrating that they will always be remembered.
2. Ronaldo's shock miss
Onto the match and after Sancho hit the crossbar inside the opening two minutes, Paul Pogba made good on his promising start after returning from injury and won the Red Devils a penalty.
The Frenchman's neat footwork drew a foul from Middlesbrough defender Anfernee Dijksteel and who else but Ronaldo would step up?
However, the script didn't go as expected, as the five-time Ballon d'Or winner dragged his effort wide to send the 9,500 travelling fans into hysterics in the stand above.
Ronaldo, who turns 37 on Saturday, looked at the turf in dismay - though his frustration from a team perspective was short-lived.
3. Sancho to the rescue
Having missed United's last two matches before the winter break due to personal reasons, Sancho returned to the starting XI and Rangnick's No.25 needed that amount of minutes to mark his return with a goal.
The winger found himself in space on the left flank and was picked out by Bruno Fernandes ' cross-field pass before driving into the box and brushing the ball past Boro goalkeeper Joe Lumley, as it nestled in the bottom right-hand corner.
Ronaldo and co breathed a sigh of relief and the Red Devils continued to pile on the pressure after taking the lead, with Marcus Rashford's fearsome drive from just outside the penalty area being ruled out for offside.
4. VAR the Crooks of the matter
As the game opened up in the early exchanges of the second half and Dean Henderson began to be called into action, Old Trafford wasn't braced for one of the most baffling referring decisions of the season.
While United's attackers had squandered chances through Rashford and Ronaldo, Middlesbrough found joy both on the pitch and at Stockley Park, as Duncan Watmore's blatant handball was ruled 'accidental' in setting up Matt Crooks to equalise.
Controlling a pass over the top, Watmore kept the ball within control with his left arm, then dinking it across goal for Crooks to finish.
The Red Devils turned to referee Anthony Taylor, fully expecting the decision to be overturned, just as the stationary Boro analysts did.
But no, the goal was given thanks to a rule change in the summer of 2021 and it was 1-1 to the bemusement of the crowd.
A proper FA Cup tie was on and after more missed chances at the Stretford End, so was extra-time.
5. Rangnick and co set unwanted record
As the length of time in the game increased, United's expected goals tally and wasteful play followed suit.
In fact, Rangnick's men missed all seven clear-cut goalscoring chances they created within the regular 90 minutes, the most they have ever managed in a game since WhoScored.com started receiving Opta data in 2009.
Much of 71,000-plus crowd grew understandably frustrated with their team's lack of cutting edge, while also going without food or drink due to "technical fault" inside Old Trafford.
It prompted anti-Glazer chants, as club legend Gary Neville weighed in on the fiasco.
6. Shoot-out drama
After an agonising 30 minutes for both sets of supporters, the tie needed a penalty shoot-out to decide who reached the fifth round.
Ex-Red Devils youngster Paddy McNair stepped up first, slotting past Henderson.
The game extra-time substitute Juan Mata, who also scored to set the back-and-forth tone.
15 perfect penalties in and Lee Peltier's strike found the top corner, with youngster Anthony Elanga firing over and ending the spectacle.
