Second-half Leicester goals from Shinji Okazaki and Islam Slimani sent Jurgen Klopp's Liverpool out of the Carabao Cup at the first hurdle.
The Reds dominated the first period in the midlands but were unable to find a way through and substitute Okazaki fired in a 67th-minute opener before Slimani lashed home a second 12 minutes from time to send the Foxes through.
Jurgen Klopp's side, who have now gone four games without a win, were not the only Premier League team to exit inside 90 minutes as Stoke and Huddersfield both fell to away losses at Bristol City and Crystal Palace respectively.
The Potters were undone by two goals in 10 second-half minutes from Famara Diedhiou and Matt Taylor, while Roy Hodgson earned his first win as Palace boss thanks to Bakary Sako's header early on.
Dele Alli's 65th-minute winner ensured Tottenham saw off Championship club Barnsley at Wembley while West Ham eased past second-tier opposition Bolton 3-0, with Angelo Ogbonna, Diafra Sakho and Arthur Masuaku all on target for the Hammers.
Paul Clement's Swansea also made into the last 16 as Alfie Mawson and Jordan Ayew struck in the second half of their 2-0 success at Reading.
Patrick Bamford bagged a brace as Middlesbrough won 2-0 against Aston Villa, who ended with 10 men due to Tommy Elphick's red card, and Norwich's Mario Vrancic also netted twice in their 3-1 victory at Brentford.