Chelsea pip Man U
Holders Liverpool ousted
Holders Liverpool, fielding a weakened side for the secondary cup competition, were knocked out by boss Brendan Rodgers' former side Swansea City 1-3 while Norwich City came from behind to beat Tottenham Hotspur 2-1.
Chelsea face Leeds United of the second tier in December while fourth division Bradford City will host Arsenal. Swansea meet second tier Middlesbrough in the last eight and Norwich will host Aston Villa.
United netted first through Ryan Giggs before David Luiz scored for Chelsea from the penalty spot. Javier Hernandez grabbed the lead back for United before defender Gary Cahill again levelled on 52 minutes. United again went in front just before the hour mark thanks to Nani's cool chip, but another penalty from substitute Eden Hazard, sent the match into extra time. Daniel Sturridge nabbed Chelsea's fourth by latching onto a poor backpass and there was even time for a Ramires goal and a Giggs penalty.
Chico grabbed the opener for Swansea in the 34th minute The weakened hosts went 2-0 down midway through the second half through Nathan Dyer before substitute Luis Suarez pulled one back and Jonathan de Guzman sealed Swansea's first ever League Cup quarterfinal spot late on.
Norwich came from behind to beat a dominant Tottenham at home with Simeon Jackson grabbing the 87th minute winner.
Karim Benzema and Kaka guided a weakened Real Madrid to a 4-1 win at third-tier Alcoyano in a King's Cup last-32 first leg in Madrid on Wednesday.
The hosts survived until the 20th-minute when Benzema headed the opener and the France striker set up Brazil midfielder and captain for the day Kaka to score the second with a low shot across the goal.
Real youth team player Jose Rodriguez curled in the third in the 66th minute, and after Alcoyano's Javi Lara had beaten Antonio Adan at his near post with a free kick, Kaka set up Benzema for the fourth near the end.
Atletico Madrid, Malaga and Real Zaragoza all won while Rayo Vallecano and Celta Vigo fell to lower league opposition.