A goal by Peter Thorne in the 11th minute gave Cardiff a 1-0 home victory over Chesterfield and moved them into second place in the Division Two table.
The decisive moment came when Thorne, at the far post, met a cross from the right and powered home a header.
But the result masked a poor Bluebirds performance against a side without a win or goal in their last four away matches.
Just before Thorne's strike, City almost went behind when Neil Alexander came out of his area to clear the ball.
It went straight to Mark Allott, but with the open goal in front of him he screwed his shot wide.
Chesterfield even missed a penalty after Chris Barker had brought down Glynn Hurst in the 21st minute, Chris Brandon blasting the spot-kick high and wide.
The visitors often looked dangerous on the break and the impressive Brandon almost atoned for his penalty blunder.
He outwitted two City defenders but his shot was stopped by Alexander.
