Sergio Aguero's late hat trick rescued Manchester City from FA Cup humiliation at the hands of second-tier Watford, ushering the Premier League title favourites into the fifth round along with Liverpool and Everton on Saturday.
The biggest shock of this season's competition was on when Watford took a 2-0 lead after 30 minutes at Etihad Stadium, only for a remarkable Aguero-led comeback by City in the final half-hour.
The Argentina striker produced clinical finishes in the 60th and 79th minutes to level the score before Aleksandar Kolarov put City in front in the 87th. Aguero completed his hat trick in injury time, keeping Manuel Pellegrini's side in contention for silverware on four fronts this season.
"I wanted to change all of my players at halftime, all 11 of them," Pellegrini said. "The whole team was a disaster in the first half."
There were no such worries for Liverpool, which beat second-tier Bournemouth 2-0 away courtesy of goals by Victor Moses and Daniel Sturridge, and Everton, which eased past third-tier Stevenage 4-0 largely thanks to Steven Naismith's first-half brace.
Everton's victory was marred by a suspected broken left leg suffered by Coast Rica international Bryan Oviedo, which could rule him out of the World Cup this summer.
Premier League teams Southampton, Cardiff, Swansea, Hull and Sunderland — a 1-0 winner over non-league side Kidderminster — also advanced but Crystal Palace, which is fighting relegation in the top flight, was eliminated after losing 2-1 at defending champion Wigan.
With Watford's starting lineup costing £500,000 ($825,000) and City's bench alone worth £84 million ($140 million), few gave the visitors a chance at the Etihad even though City fielded a weakened starting team ahead of Wednesday's Premier League match at Tottenham.
Yet Watford, a 33-1 shot with British bookmakers to beat City, stunned home fans by going into a 21st-minute lead through Fernando Forestieri before Troy Deeney made it 2-0 after 30 minutes.
All-out attack mode
By the time Aguero scored his first goal, City had four players up front and had resorted to an all-out attack mode. The striker then produced another superb finish to equalize with 11 minutes left and Watford's hopes of a replay were dashed when its goalkeeper, Jonathan Bond, let Kolarov's shot dribble from his grasp into the net.
Aguero capped the fightback by heading in Jesus Navas' cross for his 25th goal of the season, keeping up City's average of four goals per home game this campaign.
"People spoke about us losing 10-0 or 11-0 — nobody gave us a chance," Deeney said. "This is one of the biggest teams in the world but we went out there with no fear."
In 19 matches at the Etihad, only European champion Bayern Munich has left with a victory. City has won the other 18.
Arsenal began the fourth round with a comfortable 4-0 win over Coventry on Friday and Liverpool fielded a full-strength side to also enjoy an easy victory, with Moses opening the scoring in the 26th minute.
Luis Suarez set up that goal and also provided the assist for Sturridge, who ran onto the Uruguay striker's pass and slotted into the corner in the 60th. Sturridge has now scored in three straight matches since returning from nearly two months out through injury.
"The tradition in the FA Cup for Liverpool is huge and we want to pay respect to the competition because we want to get to the final and win it if we can," Liverpool manager Brendan Rodgers said.
At Stevenage, Johnny Heitinga and Magaye Gueye were the other scorers for Everton, whose manager Roberto Martinez won the FA Cup with Wigan last season. The result was overshadowed, though, by the horrific-looking injury to Oviedo in the 14th minute.
Oviedo was taken to hospital and Everton tweeted that he has a suspected broken leg.
Non-league Kidderminster's run to the last 32 has been the feelgood story of this season's competition but it came to an end at Sunderland, which was playing three days after beating Manchester United on penalties to reach the League Cup final against Man City.
Charis Mavrias scored the only goal in the fifth minute.
Southampton beat Yeovil 2-0, Swansea won 2-1 at Birmingham, Hull defeated Southend 2-0 and Cardiff was a 1-0 winner at Bolton.