Milton Keynes Dons and Port Vale knocked out Championship opposition in the Carling Cup second round on Tuesday evening.
MK Dons sent Barnsley out of the competition after a late 2-1 victory at Oakwell.
Aaron Wilbraham gave MK Dons the lead on 28 minutes before Michael McIndoe levelled for The Tykes (66).
Wilbraham became the League Two club's hero with a last-minute winner for the visitors.
League One club Port Vale heaped more misery on Championship bottom club Queens Park Rangers with a 3-2 home victory.
Marc Nygaard (9) gave QPR the lead before The Valiants struck through Jeff Smith (19), Danny Whitaker (28) and Richard Walker (61).
Damion Stewart (78) got a second for the West Londoners, but it failed to prevent QPR from going out of the competition.
Birmingham City needed extra time to see off League Two side Wrexham 4-1 at St Andrews (pictured).
Chris Llewellyn (29) gave The Dragons the lead before Cameron Jerome (41) levelled for Blues.
DJ Campbell had the chance to win the tie with a second-half penalty, but he missed his spot kick.
The match went to extra time and a brace from summer signing Gary McSheffrey (102, 113) sent Steve Bruce's side on their way before on-loan Nicklas Bendtner (117) struck Birmingham's fourth goal before end of extra time.
Caretaker boss Nigel Pearson sparked a second-half revival, as West Bromwich Albion started the post-Bryan Robson era with a 3-1 home win over Cheltenham Town.
Kayode Odejayi gave the League One side a half-time lead before Ronnie Wallwork (48) equalised for The Baggies.
A Nathan Ellington penalty on the hour mark proved to be West Brom's winner, and another spot kick from Stuart Nicholson (68) meant the Black Country club made the third round.
Leeds United eased the pressure on manager Kevin Blackwell with a 3-1 home win over League Two side Barnet.
Robert Blake (7) opened the scoring for The Whites before an Ian Moore brace (55, 74) made sure of Leeds' passage to round three, with Magno Vieira (78) striking a consolation for The Bees.
Southampton heaped more pressure on Millwall boss Nigel Spackman with a 4-0 win at The Den.
Djamel Belmadi (20) scored first before a brace from Bradley Wright-Phillips (43, 90) was followed by an injury-time strike from David McGoldrick for The Saints.
Norwich City did enough to see off Alan Knill's Rotherham United at Millmoor after a 4-2 success.
Peter Thorne (6) opened the scoring for The Canaries before Michael Keane (24) and a Lee Williamson penalty (49) turned the game around for The Millers.
Ryan Jarvis (53) then equalised for Norwich before Craig Fleming scored a minute later for the East Anglian club, and Jarvis sealed the tie with a second in injury time.
Goals by Dean Morgan (10), Warren Feeney (53) and Rowan Vine (90) gave Luton Town a 3-0 victory at League One club Brentford.
Each side had a man sent off at Griffin Park, with Brentford's Chris Moore (80) and Luton's Leon Barnett (88) handed their marching orders.
Southend United defeated managerless Brighton & Hove Albion 3-2 at Roots Hall.
Dean Cox (71) gave The Seagulls the lead before The Shrimpers won the tie with three goals in three minutes late on.
Billy Paynter (87), Lewis Hunt (88) and Freddy Eastwood (90) all struck for Southend before Adam El-Abd got a late second goal for Brighton.
Leicester City saw off the challenge of Hereford United after a 3-1 win at Edgar Street.
Elvis Hammond (27), Richard Stearman (66) and an Iain Hume penalty (76) made sure Rob Kelly's side went through, as Robert Purdie had Hereford's lone reply from the penalty spot (56).
The match saw three red cards before the end, with Leicester's Hammond (81) and Patrick Kisnorbo (89) given their marching orders by referee Richard Beeby, while Hereford's Trent McClenahan (76) was also sent off.
Finally, Hull City avoided an embarrassing exit to League Two club Hartlepool United with a 3-2 penalty shoot-out win after a goalless extra-time draw at The Kingston Communications Stadium.
Andy Dawson scored the decisive penalty for The Tigers in the shoot-out.
Click below for match summaries:
Barnsley 1-2 Milton Keynes Dons
Birmingham City 4-1 Wrexham (AET)
Brentford 0-3 Luton Town
Hereford United 1-3 Leicester City
Hull City 0-0 Hartlepool United (AET: Hull win 3-2 on penalties)
Leeds United 3-1 Barnet
Millwall 0-4 Southampton
Port Vale 3-2 Queens Park Rangers
Rotherham United 2-4 Norwich City
Southend United 3-2 Brighton & Hove Albion
West Bromwich Albion 3-1 Cheltenham Town