MK Dons, Rochdale, Shrewsbury and Brighton claimed Premier League scalps on Tuesday, with Queens Park Rangers, Norwich, Swansea and Sunderland crashing of the Carling Cup at the second round stage.
Elsewhere, Aston Villa, West Brom, Wolves, Leicester, Leeds, Nottingham Forest, Burnley, Cardiff and Millwall all marched on, avoiding any potential banana skins.
Norwich have made a steady start to life in the top flight but, having made 11 changes, they came unstuck against MK Dons, with Carrow Road old boy Luke Chadwick bagging a brace in a 4-0 win for the current leaders of League One.
Queens Park Rangers were also felled on home soil, with an early effort from Jean-Louis Akpa Akpro and a late strike from Gary Jones enough to see Rochdale into round three.
Swansea ensured that all three of the Premier League new boys bowed out on Tuesday, with Marvin Morgan, Mark Wright and Nicky Wroe on target in a memorable 3-1 victory for Shrewsbury.
Sunderland became the fourth top flight side to fall as Craig Mackail-Smith struck in extra-time to send Brighton into round three.
There was no such mishap for West Brom, as Roy Hodgson's men eased past Bournemouth 4-1 at Dean Court.
The Baggies' Black Country rivals Wolves are also in the hat following a 4-0 victory over Northampton.
Alex McLeish took Birmingham all the way last season and he is a step closer to defending that crown after seeing Eric Lichaj and Nathan Delfouneso secure a dramatic 2-0 win for Aston Villa over plucky Hereford.
Leicester survived a scare at Bury, having trailed at one stage, but eventually prevailed 4-2 in a thriller at Gigg Lane.
Nottingham Forest saw Ishmael Miller net his first goal for the club in a comfortable 4-1 win away at Wycombe.
Millwall made light work of Morecambe, who have made a bright start to the League Two campaign, with Hameur Bouazza and Tamika Mkandawire helping them to a 2-0 success.
Ramon Nunez has been among the goals for Leeds in the league of late and he was able to transfer that form into knockout competition as his double helped the Whites down Doncaster.
Cardiff were involved in an eight-goal thriller with Huddersfield, with Craig Conway and Don Cowie eventually settling a topsy-turvy encounter in extra-time.
Jay Rodriguez put four past Burton Albion in round one and he was on target again in round two as Burnley struggled to a 3-2 victory over League Two side Barnet, with Chris McCann wrapping things up in the 105th minute.