Cardiff went top of the Championship as Brighton dropped more points at home while Leicester jumped up three places to second spot with an away win.
Meanwhile, Crystal Palace upset Wolves and Burnley and Sheffield Wednesday shared a six-goal thriller at Turf Moor.
The experienced Craig Bellamy gave Cardiff the perfect start, but Leroy Lita - on loan from Swansea - equalised soon after half-time for Birmingham. However, the Bluebirds went top of the table thanks to Mark Hudson's winner as they recorded a fifth consecutive home league win.
Anthony Knockeart scored his first goal in English football with a blistering strike before adding a second as Leicester sealed their fourth league win in a row in a 2-0 success at the John Smith's Stadium against Huddersfield.
Brighton dropped down a few spots as they looked to avoid losing back-to-back games at the Amex Stadium for the first time against Ipswich. Will Buckley rescued a point with ten minutes remaining.
Blackpool climbed to fourth spot as they came out on top in a five-goal classic at the KC Stadium against Hull City. Goals from Matt Phillips, 38-year-old Kevin Phillips' first goal in 13 games and Nouha Dicko sent the Seasiders home with all three points.
Wolves had a chance to go top of the table, but dropped down to fifth position as Wilfried Zaha bagged a brace for Crystal Palace to upset the odds at Molineux.
Bolton and Leeds shared the spoils in their clash at the Reebok Stadium. Kevin Davies hit a double for Wanderers after Samuel Byram and Luciano Becchio's spot-kick put the Yorkshire side ahead.
Ten-man Watford left Charlton with a 2-1 win thanks to goals from young Tommie Hoban and Almen Abdi's stunning free-kick.
Bristol City and Millwall settled for a 1-1 draw at Ashton Gate. Steven Davies scored City's 14th home goal of the season with a prodigious header but the Lions levelled through Darius Henderson.
In arguably the game of the night Charlie Austin hit a hat-trick for Burnley to take his tally to 14 goals of a prolific season and his third hat-trick of this calendar year. But Sheffield Wednesday would not lie down and left with a point thanks to a brace from Chris O'Grady and a late effort from Michail Antonio.
Peterborough ended Barnsley's unbeaten home record as they recorded back-to-back wins following a run of seven straight defeats. George Boyd and Tyrone Barnett - his first in 13 games - helped Posh secure their second away win of the season but they still remain bottom of the table.