Shelton and Stead celebrate as they earn Sheffield United the win
Sheffield United knocked Manchester City out of the FA Cup to leave only six Premier League sides in the hat for Monday's fifth-round draw.
The Championship side took the lead when Luton Shelton netted after Michael Ball was seemingly wrong-footed by the ball bobbling off a balloon in the box.
City's Emile Mpenza and Elano both went close before Jon Stead knocked in Derek Geary's cross for United's second.
Substitute Daniel Sturridge volleyed a goal back but the hosts hung on.
Man City's travelling band of fans may have unwittingly had a hand in Shelton's opener.
A clutch of balloons littered City's goalmouth and when Lee Martin, on loan from Manchester United, crossed to Shelton, the ball momentarily got lost among them, leaving defender Ball bamboozled.
Shelton managed to keep his eye on the ball and stabbed it home to pumped fists of praise from under-pressure manager Bryan Robson.
The balloons were quickly burst, and City pressed forward in search of the equaliser.
Mpenza headed over from eight yards and Elano had two good chances; first rattling the post with his right-footed effort before seeing his free-kick from 25 yards clawed away brilliantly by Paddy Kenny .
Despite City's dominance another well-worked break brought the Blades their second goal.
Geary broke for the right-hand corner, and turned in a cross which first found Shelton before Jon Stead slotted it beyond Joe Hart.
The match, though tipped in favour of United, settled into an exciting see-saw of attack and counter-attack.
Martin Petrov was denied by a timely challenge from Leigh Bromby while Stephen Quinn blocked Darius Vassell's shot.
Kenny then flapped at a Vedran Corluka corner and Richard Dunne almost took advantage only for the ball to fly wide as United held firm.
City keeper Hart bursts the balloons after United's opener
City boss Sven-Goran Eriksson made an inspired switch at half-time replacing the increasingly wild Elano with highly-rated striker Sturridge.
Within two minutes, the teenager found himself unmarked and able to rifle home Petrov's corner for his first senior goal for City.
The play continued to swing pulsatingly from end to end. City were forced to make some desperate tackles but Martin failed to find reward from the resulting free-kicks.
Quinn headed Geary's cross just wide as the Blades harried away at City, and it looked as though Eriksson's men were running out of ideas.
With every City attack, United were ready to respond with some stout defending before punting the ball down field on the break.
Shelton found himself on course for a second only for his shot to be blocked after Vassell had fumbled the ball at the other end.
Dunne rose well to collect Petrov's free-kick but headed wide before Kenny saved from the hard-working Vassell.
Substitute Geovanni scooped the ball high and wide as City drove at the Blades defence and the home side's Billy Sharp did likewise at the other end.
United never gave up and after four minutes of added time the Championship side completed their upset, claiming the 14th Premier League scalp in this season's FA Cup.
Sheff Utd: Kenny, Geary, Bromby, Morgan, Naysmith, Gillespie, Speed, Martin, Quinn, Shelton (Tonge 76), Stead (Sharp 49).
Subs Not Used: Hendrie, Kilgallon, Armstrong.
Booked: Martin, Quinn, Morgan.
Goals: Shelton 12, Stead 24.
Man City: Hart, Corluka, Onuoha, Dunne, Ball, Elano (Sturridge 46), Hamann (Ireland 62), Gelson, Petrov, Mpenza (Geovanni 71), Vassell.
Subs Not Used: Schmeichel, Jihai.
Booked: Gelson, Corluka.
Goals: Sturridge 48.
Ref: Alan Wiley (Staffordshire).
BBC Sport Player Rater man of the match: Sheffield United's Jon Stead 8.07 (on 90 minutes). Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.