Republic of Ireland striker Sean Maguire was on target as Preston were the only convincing winners as the Carabao Cup got under way with four first-round ties.
The Lancashire side cruised into the second round with an impressive 4-0 victory over League Two Mansfield courtesy of goals from Tom Barkhuizen, Maguire, Patrick Bauer and Josh Harrop.
Barkhuizen rifled into the bottom left corner in the 14th minute before Maguire, who was left out of Stephen Kenny's first Ireland squad this week, picked out the top left corner eight minutes later.
It was 3-0 when centre-back Bauer netted from a Harrop corner before the latter wrapped up the win when he hammered in the fourth goal in the 65th minute.
Fellow Championship side Blackburn survived a scare before Adam Armstrong's late penalty secured a 3-2 victory over Doncaster in a contest which could have gone either way.
Lewis Holtby's spectacular free-kick gave Rovers a deserved lead at half-time, but the League One side turned the game on its head with two goals in the space of 10 minutes - a Fejiri Okenabirhie penalty and Madger Gomes' fierce strike.
However, Joe Rankin-Costello's first senior goal levelled matters before Armstrong's late spot-kick won it for the hosts.
Stoke needed penalties to see off League One Blackpool after the teams had shared 90 goalless minutes.
Goalkeeper Adam Davies saved from Oliver Sarkic and Keshi Anderson to take the shoot-out into sudden death after Ireland winger James McClean and Jordan Thompson failed to score for the Potters.
Bruno Martins Indi and James Husband made no mistake before Tashan Oakley-Boothe scored with the aid of a post, but Ollie Turton dragged his penalty wide of the left post to confirm the Championship club's place in the second round.
League One Portsmouth survived a scare to see off Stevenage 3-1 on penalties following a six-goal thriller at the Lamex Stadium.
Craig MacGillivray was the hero in the shoot-out, saving three Stevenage spot-kicks after Pompey had fought back from 2-0 and 3-1 down in normal time.
The Hertfordshire side, who finished bottom of League Two last season, were two goals to the good inside 10 minutes as Elliott List and Charlie Carter each capitalised on defensive mix-ups to score.
Pompey's Irish winger Ronan Curtis halved the deficit in the 20th minute, but more hesitant defending allowed Scott Cuthbert to restore Boro's two-goal cushion following a goalmouth scramble.
A Boro handball on the stroke of half-time was punished by Gareth Evans, who converted from the spot, and the visitors were level six minutes after the restart through a fine finish from John Marquis.
Curtis hit a post with nine minutes to play but neither side could find a winner before MacGillivray's heroics.