The FA Cup shock klaxon rang out at Gander Green lane as National League South side Sutton United knocked out Leeds.
Sutton were given the chance to take the lead early in the second half when Roarie Deacon went down under pressure from goalkeeper Marco Silvestri and a Leeds defender.
Jamie Collins stepped up and comfortably slotted the penalty into the bottom corner to leave Garry Monk’s side stunned.
Liam Cooper was shown a second yellow card with eight minutes remaining as the visiting side went down with a whimper.
No less than 83 places separated these teams but Leeds manager Garry Monk, clearly concentrating on promotion back to the Premier League, paid the price for making 10 changes to his line-up.
Monk’s side, packed full of youngsters and including two debutants – neither of whom were even named in the squad line-up on the back of the programme – struggled badly on Sutton’s artificial pitch.
And Collins’ second-half spot-kick ensured Sutton joined Lincoln in the fifth round – the first time two non-league teams have made it to the last 16.
Sutton have FA Cup previous, of course, having famously dumped out top-flight Coventry in the third round in 1989.
Their run to round four this season had seen them dispose of Forest Green, Dartford, Cheltenham and AFC Wimbledon to land a plum tie which evoked memories of the same fixture – at the same stage – in 1970.
That was before the days of squad rotation, with iconic names like Charlton, Bremner and Hunter running out at Gander Green Lane in a 6-0 victory.
Allan Clarke grabbed four goals that day and Peter Lorimer – a guest here on Sunday – chipped in with the other two.
But never mind being a pale shadow of that legendary side – this Leeds team did not even resemble the one which beat Nottingham Forest four days ago.
Roarie Deacon has been the talisman behind Sutton’s remarkable run with five goals, and he tormented the visitors in the first half.
The ex-Arsenal youngster hit the net after just five minutes but was adjudged offside, by surely the tiniest of margins, as the ball was touched on to him by Maxime Biamou.
Deacon was twice denied by spectacular saves from Leeds keeper Marco Silvestre, who also somehow kept out a point-blank shot from Bedsente Gomis with his backside.
All Leeds had to show for the opening 45 minutes was an effort from Stuart Dallas, who raced onto a ball over the top and tried to lift his shot over Ross Worner, only for the Sutton keeper to make a fine save.
And Sutton got the breakthrough they deserved six minutes into the second half, thanks to some shambolic Leeds defending.
Silvestre came out to meet Biamou but succeeded only in colliding with team-mate Lewie Coyle, taking the Sutton forward out and giving referee Stuart Attwell little option but to point to the spot.
Sutton skipper Collins stepped up and nervelessly sent Silvestre the wrong way to spark wild celebrations on the old-style terraces behind the goal.
As if Leeds’ afternoon could not get any worse, they were reduced to 10 men with 10 minutes left after captain Liam Cooper was sent off for a foul on Craig Eastmond.
Attwell’s whistle at the end prompted a joyous pitch invasion as humiliated Leeds made a hasty exit towards the tunnel.
The Elland Road side have bigger fish to fry and this chastening defeat will be a distant memory should they go on and clinch promotion, but it was another day for the Sutton fans to cherish.