Second-tier Watford were half an hour away from a seismic FA Cup shock at Manchester City today before Sergio Aguero ruined the script with a hat-trick as his side stormed back to reach the last 16 with a 4-2 win.
Only European champions Bayern Munich had returned victorious from City's Etihad Stadium fortress this season but goals by Fernando Forestieri and Troy Deeney had the Watford fans dreaming of a famous result.
The London side were still leading 2-0 after an hour but eventually succumbed to the siege as Aguero cancelled out the deficit, Aleksandar Kolarov put City ahead three minutes from time and their Argentina striker completed a treble to maintain Manuel Pellegrini's side's four-pronged assault on silverware.
Liverpool had no such problems as they reached the last-16 with a 2-0 win at second tier Bournemouth - Victor Moses and Daniel Sturridge scoring for the seven-times winners.
Kidderminster, the only survivors from outside England's top four divisions, battled valiantly at League Cup finalists Sunderland but slipped out 1-0 while fourth tier Southend United were beaten 2-0 at home by Premier League Hull City.
Holders Wigan Athletic, who were relegated to the Championship after beating Manchester City in last year's final, kept alive their hopes of an unlikely successful defence of the trophy with a 2-1 win over top flight Crystal Palace.
Apart from Palace's exit there were no other surprises with Wilfried Bony's double helping Swansea City triumph 2-1 at Birmingham City, Cardiff City winning 1-0 at Bolton Wanderers and Southampton easing past second tier side Yeovil Town 2-0.
Championship sides Brighton and Hove Albion and Charlton Athletic are also in Sunday's fifth round draw, as are three-times winners Sheffield Wednesday who ended the hopes of fourth-tier Rochdale, winning 2-1 away despite finishing with 10 men.
Later on Saturday, Everton are away at third-tier Stevenage while Chelsea host Stoke City on Sunday. Premier League leaders Arsenal reached the fifth round on Friday with a 4-0 victory over Coventry City at The Emirates.
CITY RECOVER
Even diehard Watford fans would have feared the worst as their side ventured north to Manchester to face a City side who have trounced the likes of Arsenal, Tottenham Hotspur and Manchester United at home this season.
City began the match with 106 goals already in the tank from the four competitions they are contesting, the majority of them at home, and a strong lineup.
But they fell behind after 21 minutes when Forestieri fired through the legs of goalkeeper Costel Pantilimon.
Nine minutes later the side that are 15th in the Championship extended their lead through Deeney to send their 3,500 travelling fans into delirium.
City boasted an attacking quartet of Stevan Jovetic, Edin Dzeko, Aguero and Jesus Navas after the break and once Aguero clinically pulled a goal back on the hour there was a sense of inevitability about the outcome.
Aguero curled home the equaliser in the 79th and, after Kolarov's weak shot somehow got past Watford keeper Jonathan Bond three minutes from time, Aguero completed the turnaround with his head to maintain City's four-goal average at home.