Malky Mackay's Bluebirds failed to crack Huddersfield Town's sturdy defence as the fast-sinking Terriers held out for a goalless draw against the pacesetter at the John Smith's Stadium.
But the point proved enough to strengthen Cardiff's promotion push after Leicester City's run of five straight league wins came to an unexpected end against Peterborough United at London Road.
Ben Marshall had swept Leicester in front in the 52nd minute but Davide Petrucci lashed home a 74th-minute equaliser, then Grant McCann gave Posh a priceless 2-1 win with his 88th-minute strike.
Middlesbrough's hold on the final play-off place looks increasingly fragile after Tony Mowbray's side suffered its fourth straight league defeat in a 3-2 loss to Barnsley.
Jim O'Brien hit an early opener for the visitor but Boro clawed its way back to lead with goals from Mustapha Carayol and substitute Curtis Main early in the second half.
But the Tykes replied with a 70th-minute equaliser from Scott Golbourne then veteran Jason Scotland hit the winner six minutes later to stretch his side's unbeaten run to seven games.
Blackburn Rovers looks best placed to capitalise on Boro's mighty wobble after it edged to a 1-0 win over Ipswich Town at Ewood Park, the winner credited as an own goal to Ipswich goalkeeper Stephen Henderson after a goalmouth scramble on the hour.
Billy Davies knows the size of his task when he returns as Nottingham Forest boss on Monday after it slid to a 2-0 defeat at Bristol City, managed by former Forest boss Sean O'Driscoll.
Stephen Davies put O'Driscoll's men ahead in the 50th minute and Marvin Elliott added the second on 62 to boost City's survival fight and hand Forest its third straight loss.
David Ngog's 81st-minute winner won a bustling Lancashire derby for Bolton Wanderers over Burnley at the Reebok Stadium.
David Edgar headed home a Junior Stanislas corner to give the visitor the lead on 55 minutes before Bolton substitute Craig Davies headed an equaliser on 66.
Ngog eased Bolton's relegation worries when he pounced in box after following up Jay Spearing's initial effort to give his side a 2-1 win.
Nathan Delfouneso's injury-time effort sealed a dramatic 2-1 win for Blackpool against Millwall at Bloomfield Road.
James Henry put the Lions ahead direct from his 32nd-minute corner, but Tom Ince equalised on the hour for Blackpool before Delfouneso lashed home from deep inside the box.
Danny Batth scored in the second minute of injury-time to give struggling Wolverhampton Wanderers a point in a 2-2 draw with Leeds United at Molineux.
Lee Peltier's 57th-minute own goal put Wolves in front but Luke Varney equalised and Ross McCormack looked to have won it for Leeds with a 78th-minute penalty before Batth prodded home the late equaliser.
Sheffield Wednesday fought back from two goals down to share the points in a 2-2 draw with Derby County at Hillsborough.
Jeff Hendrick put the Rams in front and Jamie Ward made it 2-0 from a 48th-minute penalty after being fouled by Miguel Llera in the box.
Leroy Lita pulled a goal back for Wednesday in the 51st minute then Llera equalised with a 57th-minute header from Michail Antonio's cross.
There was late drama at The Valley where Yann Kermogant looked to have claimed the points for Charlton Athletic with an 88th-minute opener, only for Wade Elliott to grab a 1-1 draw for Birmingham City in the fourth minute of injury-time.
In the day's late kick-off, a late free-kick from Brighton & Hove Albion substitute Vicente Rodriguez at home to Hull City was enough to give
the Seagulls maximum points and take them up to fourth, two points off