Cardiff saw their lead at the top of the Championship trimmed to a single point as a 3-1 defeat at Colchester, coupled with a 3-0 win for second-placed Preston were over Luton saw North End gain ground.
After a goalless first half at Layer Road, Kevin McLeod gave Colchester a 49th-minute lead, but the prolific Michael Chopra levelled the scores in the 66th minute.
However, Colchester finished strongest and made sure of a sixth successive home win courtesy of goals from Jamie Guy (84) and Jamie Cureton's penalty (90) - awarded following a professional foul by Stephen McPhail - who was sent off - on Ritchie Jones.
High-flying Preston continue to impress under Paul Simpson with a hat-trick of unanswered second-half goals enough to see off 10-man Luton.
Graham Alexander's 52nd minute penalty - from an incident which saw Hatters goalkeeper Marlon Beresford sent off - and close-range finishes from Patrick Agyemang (60) and Brett Ormerod (87) were the least the hosts deserved for a dominant display.
Lancashire rivals Burnley needed an injury-time header from Chris McCann to see off Ipswich at Turf Moor and retain third place - the Clarets' Micah Hyde was sent off just before the end after picking up a second yellow card.
Birmingham stayed fourth in the table courtesy of Radhi Jaidi's 75th-minute goal at Plymouth, who slip out of the top six.
Wolves replaced Argyle in the play-off zone after a 3-1 win over rock bottom Southend at Molineux.
The hosts led 3-0 by the 22nd minute, with goals from Leon Clarke (10 and 22) sandwiching a rare effort from central defender Jody Craddock (12). Matt Harrold pulled a goal back for the Shrimpers in the 57th minute.
Two goals in three minutes turned the game at Pride Park on its head - with Derby beating West Brom 2-1 to move up to eighth.
Richard Chaplow's 26th minute goal gave Albion the lead but Matt Oakley (69) levelled the scores and England Under-19 international Giles Barnes scored his fourth goal in three games in the 72nd minute to set up a home win.
At the other end of the table, Barnsley moved out of the relegation zone at the expense of Leeds - after winning the Yorkshire derby between the teams at Oakwell 3-2.
Martin Devaney gave Barnsley the lead after 30 minutes - but Leeds turned things round in a little more than two minutes just before the break courtesy of Shaun Derry and Robbie Blake.
But Michael McIndoe levelled the scores just past the hour mark - and Brian Howard's 76th-minute goal was a fitting winner.
Hull are the other team occupying a place in the drop zone - despite picking up a point in a 0-0 draw at Southampton.
Robert Earnshaw's 51st-minute goal moved Norwich above today's Carrow Road opponents Sunderland, while Sheffield Wednesday picked up their fourth successive home win.
Marcus Tudgay took his tally to five goals in four games with efforts after 34 and 55 minutes sealing a 2-1 victory over Leicester, who replied through Matt Fryatt (72).
And QPR won an entertaining London derby against Crystal Palace 4-2 at Loftus Road, coming from 1-0 and 2-1 down to do so.
Tom Soares (30) and Clinton Morrison (43) had Palace 2-1 up at the break but goals from Jimmy Smith (34 and 69), Steve Lomas (59) and Kevin Gallen (penalty, 66) moved John Gregory's team five points clear of the relegation zone.