This follows a number of shock results in the third round ties played on Saturday.
Newcastle United suffered an embarrassing 1-0 home defeat by third-tier Cambridge United.
Joe Ironside netted a second-half goal and goalkeeper Dimitar Mitov made a series of superb saves to seal a famous victory at St James’ Park.
Burnley were another Premier League casualty, as they lost 2-1 to Huddersfield Town.
The visitors came from a goal down to win late on through Matty Pearson’s 87th-minute header from a corner. Jay Rodriguez’s header had given Sean Dyche’s men the lead, but Josh Koroma equalized in the 74th minute.
Leicester, who are the current holders of the cup, saw off Watford 4-1, with goals by Youri Tielemans, James Maddison, Harvey Barnes and Marc Albrighton.
Chelsea, Everton, Southampton and Brentford are, however, all through to the next round of the competition.