Manchester City were the victims of the biggest FA Cup shock of the day as they were comfortably beaten at home by the Championship's Nottingham Forest.
Forest took the lead when a defensive error by Micah Richards allowed Nathan Tyson to unleash an unstoppable dipping volley from 20 yards.
Robert Earnshaw then doubled Forest's advantage when the Welshman turned home Matt Thornhill's misdirected shot.
Joe Garner made sure of the win after a sloppy bit of play from Didi Hamann.
Defeat to a team that is hovering just above the Championship's relegation zone on goal difference will surely increase the pressure on City manager Mark Hughes.
The Welshman has so far been backed by the club's Abu Dhabi-based owners despite a disappointing start to the season, but he will undoubtedly feel the heat after this poor display.
Forest were deserving of a victory masterminded by caretaker manager John Pemberton, with new boss Billy Davies, who takes charge on Monday, watching from the stands.
New £10m signing Wayne Bridge was paraded at Eastlands before kick-off and barely a minute into the game it was evident why Hughes' first signing of the transfer window had been a defensive one.
Tyson's cross found the unmarked Lewis McGugan at the far post and the Forest man, who along with Thornhill had dominated in midfield, should have done better with his header.
606: DEBATE
Forest took the lead when England international Richards failed to deal with a routine long ball, allowing Tyson space to score in spectacular style before Earnshaw added to City's woes.
City were without their Brazilian playmaker Robinho and the injured Stephen Ireland, but nevertheless fielded a strong side which was unsurprisingly greeted to a cacophony off boos as they made their way down the tunnel at the break.
Daniel Sturridge, the catalyst of City's magnificent comeback at Blackburn last week, had a couple of efforts on goal, the best of which was a lofted shot as Paul Smith advanced.
And Jo would probably have pulled a goal back if Wes Morgan had not made a brave block 20 minutes from the end.
However, City's missed chances were all made irrelevant when substitute Hamann failed to spot Garner lurking as he tried to find Richard Dunne with a throw-in and the young midfielder gleefully drove home.
Man City: Hart, Zabaleta, Richards, Dunne, Ball, Elano, Fernandes (Hamann 60), Kompany, Wright-Phillips (Vassell 24), Caicedo (Jo 70), Sturridge.
Subs Not Used: Schmeichel, Garrido, Clayton, Berti.
Booked: Dunne.
Nottm Forest: Smith, Morgan, Breckin, Perch (Wilson 17), Chambers, Anderson, McGugan, Cohen, Thornhill, Tyson (Davies 81), Earnshaw (Garner 73).
Subs Not Used: Richardson, Byrne, Heath, Reid.
Goals: Tyson 38, Earnshaw 42, Garner 75.
Att: 31,869
Ref: Lee Probert (Wiltshire).
BBC Sport Player Rater man of the match: Nottingham Forest's Nathan Tyson 8.75 (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.
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