Morecambe made a stunning Carling Cup debut by knocking out Lancashire rivals Preston 2-1 in the first round at Deepdale on Tuesday night.
The Shrimps, newly promoted to the Football League, took a sixth-minute lead through Jim Bentley's volley from a Craig Stanley cross.
Danny Pugh headed a 73rd-minute equaliser for the Championship side but Sammy McIlroy's team went back in front with six minutes to go as David Artell netted a dramatic winner.
Leicester earned their first competitive win under Martin Allen with a narrow 1-0 win over Accrington at the Crown Ground to book their place in the second round.
The Foxes won this competition in 2000 and made it through thanks to James Wesolowski's goal in the fourth minute. It made some amends for a poor start in the league for Allen's men, who lost 1-0 at home to Blackpool on the opening day.
Charlton avoided a shock against 1969 winners Swindon, winning 2-0 at the County Ground.
Darren Ambrose scored the Addicks' first in the 52nd minute after a header down by Marcus Bent and Andy Reid added the second with a retaken penalty in the 63rd minute.
Norwich, who won the competition in 1962 and 1985, thrashed League Two side Barnet 5-2 to go through.
A Jamie Cureton brace (three and 16) set them on the way before Simon Lappin (21), Mark Fotheringham (25) and Darel Russell (31) put an added gloss on the scoreline for Peter Grant's team. Jason Puncheon and Adam Birchall scored second-half consolation goals for the Londoners.
Bristol City won 3-0 at Brentford as Marvin Elliott (16) put them in front and Phil Jevons added a second for the Robins as he smashed the ball in from Enoch Showunmi's pass in the 42nd minute. Jevons grabbed his second and City's third with four minutes left.
Coventry progressed comfortably with a 3-0 win over Notts County at the Ricoh Arena. Dele Adebola's curling 47th-minute effort gave them the lead and an exquisite lob by Leon Best after 66 minutes put them in control. Robbie Simpson added a third for the Sky Blues with 12 minutes to go.
Plymouth were 2-1 victors at home to Wycombe, with a Martin Bullock own goal (41) giving them the lead and Lee Hodges (45) added a second just before half-time at Home Park. Stefan Oakes' deflected long-range shot (76) gave the Chairboys hope.
Championship new boys Blackpool won 1-0 at home to Huddersfield thanks to Ben Burgess' 75th-minute goal.
Leyton Orient claimed a shock 2-1 win in their all-London clash with QPR at Loftus Road.
Jason Demetriou (55) put the Os in front, and Adam Boyd added a second from the penalty spot nine minutes later. The Championship team pulled one back through Martin Rowlands in the 68th minute, but Martin Ling's men were not to be denied.
Leeds will keep their fingers crossed for a second-round glamour tie to boost their finances, after the League One side edged past Macclesfield 1-0 - Ian Westlake netting the only goal in the 78th minute for Dennis Wise's side.
Bristol Rovers took the shock scalp of Crystal Palace, winning 4-1 on penalties after a 1-1 draw at the Memorial Stadium.
Rochdale were denied a victory in extra-time by a late Richard Cresswell goal for Stoke which forced a 2-2 draw, but Dale recovered to win 4-2 in the shoot-out.
MK Dons won a topsy-turvy match against Ipswich on penalties after a 3-3 draw. Kevin Gallen's 120th-minute penalty took the match to a shoot-out after Owen Garvan's 98th-minute goal appeared to have completed a comeback for Ipswich.
League Two side Shrewsbury caused a stir by knocking out Championship Colchester 1-0, with a Darren Kempson goal in the 106th minute at the New Meadow.
Cardiff beat Brighton 1-0 with a Roger Johnson goal in the 110th minute, while Burnley won 4-2 on penalties at Grimsby after a 1-1 draw at Blundell Park.