Chelsea and Manchester City may have been the biggest casualties in Saturday's FA Cup fourth ties but there were plenty of other shocks too.
Tottenham and Southampton both lost at home to fellow Premier League sides, while Swansea crashed out to Championship side Blackburn.
Late goals from Leonardo Ulloa and Jeffrey Schlupp saw Leicester hit back from behind to beat Spurs 2-1 at White Hart Lane.
The Londoners looked set to ease home in a low-key encounter after Andros Townsend hit a 19th-minute penalty past 42-year-old Foxes debutant Mark Schwarzer.
But Ulloa steered home a low left-foot equaliser before Dutchman Schlupp stole the show deep into injury time with another left-foot strike.
Marouane Chamakh scored twice to continue Alan Pardew's winning run as Crystal Palace boss with a 3-2 victory over Southampton at St Mary's.
All five goals came in a breathless first 39 minutes with Graziano Pelle putting Saints in front on nine minutes before Chamakh equalised two minutes later.
A Scott Dann own goal restored the hosts' advantage but Yaya Sanogo's rising effort equalised for the Eagles and Chamakh got his second six minutes before the break.
Nine-man Swansea were the third top-flight casualties against lower level opposition as they crashed out 3-1 at Blackburn in the lunchtime kick-off.
Rudy Gestede fires in Blackburn's second goal against Swansea in teh fourth round of the FA Cup.
The visitors had Kyle Bartley sent off after only seven minutes but still took the lead when Gylfi Sigurdsson struck a stunning opener three minutes later.
But Rovers drew level two minutes later through Chris Taylor and substitute Rudy Gestede put the home side in front 12 minutes later.
Craig Conway made it 3-1 in the 89th minute before Sigurdsson was sent off for a reckless lunge on Taylor in injury time.
Two goals from Victor Anichebe helped West Brom survive a tricky test against Midlands rivals Birmingham at St Andrew's.
The Baggies made the most of a sloppy start from the hosts with Anichebe hitting the opener on 25 minutes and notching his second 10 minutes later.
But the Blues rallied and made a game of it after Jonathan Grounds reduced the deficit with a low shot off the post in first-half injury time.
Sunderland had Jack Rodwell sent off as they battled out a dismal goalless draw against Fulham at the Stadium of Light.
Rodwell had already been booked when he senselessly blocked a throw by Fulham keeper Marcus Bettinelli in the 66th minute, leading to his dismissal.
Darren Bent headed the opener on his full debut as Derby beat neighbours Chesterfield 2-0, Will Hughes completing a hard-earned victory for the Championship side with eight minutes to go.
Substitute Hal Robson-Kanu grabbed a fifth round place for Reading as the Royals came from behind to beat Cardiff 2-1 in south Wales.
Kenwyne Jones's 25th-minute header put the Bluebirds in front before Oliver Norwood equalised and Robson-Kanu pounced to win it two minutes from time.
Preston and Sheffield United must do it again after a 1-1 draw at Deepdale, Paul Gallagher putting the hosts in front before Diego De Girolamo equalised midway through the second half.
