Cardiff City ended a run of three games without a win to open a seven-point lead at the top as Sheffield Wednesday edged nearer the relegation zone.
A poor first half ended with Don Cowie breaking the deadlock with a driven shot from the edge of the area after Wednesday failed to clear a corner.
Another set-piece saw the unmarked Matthew Connolly double the lead with a close-range header.
Miguel Llera's 70th-minute free-kick was a rare effort from the home side.
With relegation rivals Peterborough and Wolves both winning, the defeat leaves former Bluebirds boss Dave Jones's Owls only one point clear of the bottom three.
- Peter Whittingham made his 300th appearance for the Welsh club
While lacking polish, due in part to the poor state of the Hillsborough pitch, Cardiff showed real grit and determination to grind out a victory that will help ease some doubts about whether they can keep their nerve in the run-in.
Their 11-point lead at the start of February has slowly been eroded by the chasing pack over recent weeks and it stood at only four points prior to the game in South Yorkshire.
But the advantage has a commanding feel once more as Cardiff's victory coincided with defeats for their nearest rivals, Hull City and Watford.
An uneven and patchy pitch hindered any hope of flowing football. Coupled with the anxiety for points - for contrasting reasons - entertainment and goal-scoring opportunities were at a premium.
And not for the first time this season, set-pieces proved decisive as the Bluebirds won their 10th away league game.
Having barely managed a shot during the opening period, the visitors broke the deadlock moments before half time from an unlikely source.
Craig Bellamy's whipped delivery caused concern in the home six-yard box and was only half-cleared to Cowie on the edge of the area. The midfielder's low drive found its way into the net through a forest of legs for only his second goal of the season.
The opener failed to change the nature of a scrappy game, but the visitors had few complaints as another well-delivered set-piece led to a second goal 20 minutes into the second half.
Peter Whittingham's in-swinging free-kick found an inviting space between Chris Kirkland and Wednesday's back four, and as the goalkeeper hesitated on his line, Connolly arrived unmarked to head in low from six yards.
It was not until 20 minutes from time that Cardiff goalkeeper David Marshall had to make his first save, tipping Llera's free-kick over the bar.
Leroy Lita, on loan from Swansea City, had an effort ruled out for offside as Wednesday piled forward. The visitors survived a late goalmouth scramble, but in truth they always looked in control.
Sheffield Wednesday manager Dave Jones:
"There was nothing in it at all. We spoke about how they like to build pressure by winning set-pieces and putting the ball in the box and we spoke about how to stop it.
"But we've switched off at key times and that's disappointing.
"We've shown a little bit of naivety where maybe they've got that edge of experience over us."
Cardiff City manager Malky Mackay:
"It's another three points towards where we want to go. We've been top since November 24 and it's a long time to be there and be shot at, discussed, debated - I'm very pleased with the mental strength of our players to deal with that.
"They just keep taking on the team that's in front of them and going on to the next one.
"We were up against a side who need to win games to stay out of the relegation zone so we knew it would be a battle.
"You have to keep entering into those battles and eventually you start to win them. We kept at it and got the result we deserved."
- 01 Kirkland
- 02 Buxton
- 03 R Johnson
- 04 Gardner Booked
- 32 Llera
- 07 Antonio (Maguire - 77' )
- 15 Helan (J Johnson - 68' Booked )
- 19 Pugh (Madine - 56' )
- 20 Lee
- 25 Prutton Booked
- 24 Lita
- 43 Bywater
- 05 Taylor
- 06 Semedo
- 11 J Johnson
- 16 McCabe
- 09 Madine
- 10 Maguire
- 01 Marshall
- 03 Taylor
- 12 Connolly
- 25 Barnett
- 31 Nugent
- 07 Whittingham
- 08 Cowie
- 17 Gunnarsson
- 22 Helguson Booked (Gestede - 87' )
- 27 Campbell
- 39 Bellamy Booked (Smith - 81' )
- 32 Lewis
- 02 McNaughton
- 11 Conway
- 13 Kim Bo-Kyung
- 18 Mutch
- 14 Smith
- 15 Gestede
Live Text Commentary
Full Time The final whistle goes and the game is over.90:00 +5:01
The assistant referee signals for offside against Leroy Lita. Free kick taken by David Marshall.90:00 +4:40
Effort on goal by Fraizer Campbell from inside the penalty area goes harmlessly over the bar.90:00 +2:13
Free kick taken by David Marshall.90:00 +2:13 Booking
Booking Jermaine Johnson booked.90:00 +2:05
Fraizer Campbell fouled by Jermaine Johnson, the ref awards a free kick.90:00 +1:41
Anthony Gardner takes a shot. Save by David Marshall.90:00 +0:58
Corner taken right-footed by Chris Maguire.88:43
The official flags Leroy Lita offside. Indirect free kick taken by David Marshall.87:26
Fraizer Campbell is ruled offside. Chris Kirkland restarts play with the free kick.86:26
Free kick taken by David Marshall.86:26 Substitution
Substitution Heidar Helguson leaves the field to be replaced by Rudy Gestede.86:26
Miguel Llera is penalised for a handball.85:25
Indirect free kick taken by Chris Kirkland.85:25 Booking
Booking Caution for Heidar Helguson.85:17
Unfair challenge on Chris Kirkland by Heidar Helguson results in a free kick.84:19
Fraizer Campbell concedes a free kick for a foul on Lewis Buxton. Chris Kirkland restarts play with the free kick.82:10
Andrew Taylor takes the inswinging corner, Unfair challenge on Anthony Gardner by Leon Barnett results in a free kick. Chris Kirkland restarts play with the free kick.80:55 Substitution
Substitution Tommy Smith replaces Craig Bellamy.79:36
Free kick awarded for a foul by Ben Nugent on Kieran Lee. Miguel Llera fires a strike on goal direct from the free kick, save by David Marshall.
Fraizer Campbell fouled by Anthony Gardner, the ref awards a free kick. Indirect free kick taken by David Marshall.77:58 Booking
Booking The referee cautions Craig Bellamy for unsporting behaviour.77:40
Craig Bellamy challenges Reda Johnson unfairly and gives away a free kick. Indirect free kick taken by Anthony Gardner.76:34 Substitution
Substitution Chris Maguire replaces Michail Antonio.68:46
Don Cowie gives away a free kick for an unfair challenge on Michail Antonio. Miguel Llera has a direct shot on goal from the free kick, David Marshall makes a save. Corner taken by Michail Antonio from the left by-line, Anthony Gardner gives away a free kick for an unfair challenge on Heidar Helguson. David Marshall takes the free kick.67:28 Substitution
Substitution Jeremy Helan goes off and Jermaine Johnson comes on.66:43
The referee blows for offside against Heidar Helguson. Chris Kirkland takes the indirect free kick.64:33
Assist by Andrew Taylor.64:33 Goal scored
Goal! - Matthew Connolly - Sheff Wed 0 - 2 Cardiff Matthew Connolly scores a headed goal from inside the six-yard box. Sheff Wed 0-2 Cardiff.63:54
Heidar Helguson fouled by Reda Johnson, the ref awards a free kick. The free kick is delivered left-footed by Andrew Taylor from right wing,62:48
Miguel Llera is ruled offside. Indirect free kick taken by David Marshall.60:55
Lewis Buxton sends in a cross, Unfair challenge on Leon Barnett by Gary Madine results in a free kick. David Marshall takes the free kick.60:08
The referee blows for offside against Craig Bellamy. Indirect free kick taken by Chris Kirkland.59:16
Ben Nugent concedes a free kick for a foul on Michail Antonio. Lewis Buxton restarts play with the free kick.58:08
Heidar Helguson concedes a free kick for a foul on Anthony Gardner. Chris Kirkland restarts play with the free kick.55:44 Substitution
Substitution (Sheff Wed) makes a substitution, with Gary Madine coming on for Danny Pugh.55:08
Inswinging corner taken by Andrew Taylor.54:07
Shot from just outside the box by David Prutton goes over the bar.48:09
The referee blows for offside. Indirect free kick taken by Chris Kirkland.45:48
Free kick awarded for an unfair challenge on Leon Barnett by Jeremy Helan. David Marshall takes the free kick.45:01
The match restarts for the second half.45:00 +2:37 Half time
Half Time The half-time whistle blows.44:49 Goal scored
Goal! - Don Cowie - Sheff Wed 0 - 1 Cardiff Don Cowie gets on the score sheet with a goal from just inside the penalty area to the bottom left corner of the goal. Sheff Wed 0-1 Cardiff.44:18
Corner taken right-footed by Craig Bellamy,42:22 Booking
Booking Anthony Gardner receives a yellow card for dissent.42:13
Free kick awarded for a foul by Anthony Gardner on Heidar Helguson. Peter Whittingham takes the direct free kick.41:37
The referee blows for offside against Fraizer Campbell. Indirect free kick taken by Chris Kirkland.39:24
Michail Antonio crosses the ball, Ben Nugent manages to make a clearance. Inswinging corner taken left-footed by Danny Pugh from the right by-line.37:22
The official flags Fraizer Campbell offside. Free kick taken by Chris Kirkland.36:36 Booking
Booking David Prutton is cautioned by the ref for unsporting behaviour.36:04
David Prutton concedes a free kick for a foul on Fraizer Campbell. Free kick taken by David Marshall.35:16
Ben Nugent gives away a free kick for an unfair challenge on Michail Antonio. Direct free kick taken by Michail Antonio.34:14
Peter Whittingham takes a inswinging corner to the near post, Fraizer Campbell concedes a free kick for a foul on Chris Kirkland. Free kick taken by Chris Kirkland.28:47
The referee blows for offside. Ben Nugent restarts play with the free kick.24:49
Free kick awarded for a foul by Leon Barnett on Leroy Lita. Danny Pugh takes the free kick.15:40
Corner taken short by Peter Whittingham.11:30
Free kick awarded for an unfair challenge on Michail Antonio by Ben Nugent. Free kick crossed by Danny Pugh, save by David Marshall.10:44
Ben Nugent concedes a free kick for a foul on Miguel Llera. Chris Kirkland restarts play with the free kick.7:54
Chris Kirkland fouled by Leon Barnett, the ref awards a free kick. Free kick taken by Chris Kirkland.7:01
Craig Bellamy takes a inswinging corner from the left by-line played to the near post.6:14
Fraizer Campbell concedes a free kick for a foul on Lewis Buxton. Chris Kirkland restarts play with the free kick.2:20
Jeremy Helan takes a shot. Save made by David Marshall.1:44
Michail Antonio takes a shot. Blocked by Don Cowie.0:00
The referee gets the game started.
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