Derby beat Burnley in a stormy encounter at Pride Park to move six points clear at the top of the Championship as Southend stunned their nearest rivals Birmingham at St Andrew's.
Freddy Eastwood was among the scorers for the bottom club as they came from behind to win 3-1 after conceding an early own goal through Peter Clarke (5).
Kevin Maher pulled The Shrimpers level on 22 before Eastwood fired them ahead three minutes into the second half with his 50th league goal for the club. Mark Gower completed the scoring six minutes from time.
At Pride Park, referee Mike Riley sent off both managers and Burnley's Eric Djemba-Djemba as Derby won 1-0.
Steve Howard scored the only goal in the fourth minute before County boss Billy Davies was sent to the stands after disputing a decision.
Djemba-Djemba was shown his second yellow card in the last minute, before Steve Cotterill became involved in a confrontation with former Burnley full back Mo Camara.
Preston also lost ground at the top of the table as they became Colchester's latest victims at Layer Road.
David Nugent missed several chances for Paul Simpson's men, before Garry Richards (67) scored to give United a 1-0 win - their 12th victory in a 13-match unbeaten home run.
Sunderland missed their chance to close on the leaders as they were held to a 0-0 draw by Crystal Palace at The Stadium of Light.
Stoke were also held to a goalless draw at home, with Ipswich the visitors to The Britannia Stadium, but Wolves were able to boost their play-off hopes as their nine men held out for a 1-0 win at Norwich.
Winger Michael Kightly (53) scored the only goal shortly before Gary Breen was sent off for hauling down Darren Huckerby. Mick McCarthy's men then had Jackie McNamara sent off in injury time.
At the bottom of the table, Leeds dragged Hull back into trouble with a 2-1 win at The KC Stadium.
Matt Heath (21) scored first for the visitors, but Nicky Forster (45) scrambled in an equaliser for Hull moments before the break.
Alan Thompson, who scored with a curling free-kick on his debut against West Brom, repeated the trick on 50 minutes to give Dennis Wise's men the points.
Barnsley have been replaced in the relegation zone by Queens Park Rangers after beating John Gregory's men 2-0 at Oakwell.
The Tykes scored in the last minute of each half, with Marc Richards netting the opener and Brian Howard making sure of the points.
Finally, Luton dropped to 21st place after going down 1-0 at Coventry, where Leon McKenzie (76) scored the only goal to end City's miserable run of form.
Click below for match summaries:
Barnsley 2-0 Queens Park Rangers
Birmingham City 1-3 Southend United
Colchester United 1-0 Preston North End
Coventry City 1-0 Luton Town
Derby County 1-0 Burnley
Hull City 1-2 Leeds United
Norwich City 0-1 Wolverhampton Wanderers
Stoke City 0-0 Ipswich Town
Sunderland 0-0 Crystal Palace