Last year's beaten finalist Cardiff City crashed out of the Capital One Cup in the first round after blowing an early lead to go down 2-1 at League Two Northampton Town.
Bristol City was the third Championship side to crash out as it was beaten 2-1 by Gillingham at Ashton Gate.
Birmingham City survived an early scare against League Two Barnet at St Andrew's when
The Blues blazed back with a
Crystal Palace was also forced to come from behind to beat Exeter City 2-1 at St James Park.
League Two Bristol Rovers took a surprise 26th-minute lead at Ipswich Town through
Burnley was yet another Championship side forced to come from behind as
There were no such problems for Leicester City, which won 4-0 at Torquay United with goals from
Crisis club Portsmouth crashed 3-0 at Plymouth Argyle, while another newly-relegated side, Coventry City, squeaked past League Two Dagenham & Redbridge with
League One Stevenage beat AFC Wimbledon 3-1 and Yeovil Town won an all-League One clash 3-0 at home to Colchester United.
League One Scunthorpe United staged a stupendous comeback to knock out Championship Derby County 7-6 on penalties at Pride Park after a 5-5 draw in normal time.
Nigel Clough's Rams led 3-0 and 5-3 before the Iron forced an extra half-hour by scoring twice in injury-time through a Connor Jennings strike and Bobby Grant's last-gasp penalty.
Newly-promoted Charlton Athletic was another Championship side to fall as it went down 4-3 on penalties to League One Leyton Orient at The Valley.
Scott Wagstaff gave Charlton a 28th-minute lead but Mathieu Baudry equalised in first-half injury-time and the visitor held its nerve to win 4-3 in the shootout with Ryan Brunt firing home the decisive kick.
And Millwall also missed out on penalties to League One Crawley Town at the New Den.
Hope Akpan and Nicky Adams twice put the visitor ahead only for the Lions to haul their way back through Darren Ward and Shaun Batt respectively.
But the visitor eased through the eventual shootout 4-1 with Crawley goalkeeper Paul Jones the hero as he saved from Darius Henderson and Jack Smith.
Abdulai Bell-Baggie scored in the last minute of extra-time to give Tranmere Rovers a 2-1 win at Chesterfield, while League Two Oxford United pulled off a minor upset with a 5-3 penalty win over AFC Bournemouth after a goalless draw.
League Cup sponsors Capital One have declared themselves "absolutely delighted" with the first season of their four-year deal.