Victory would have taken the south-coast side a point clear of leaders Newcastle United, who lost at Nottingham Forest on Friday night, but they could not prise open the Cardiff defence - and played stoppage time with 10 men after Gaeten Bong was sent off.
Third-placed Reading could not close the gap on the top two, crashing 5-0 at Fulham as their five-game winning run came to a spectacular halt.
Norwich City also hit five as they returned to form after five defeats on the bounce, demolishing Brentford 5-0 to edge back into the promotion playoff spots.
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Preston fell to a 2-1 defeat at Sheffield Wednesday after two of their players, Eoin Doyle and Jermaine Beckford, were sent off for fighting each other. Wednesday had already lost Fernando Forestieri to a red card.
Fourth-placed Birmingham City crashed to a 3-0 home defeat to Barnsley. Leeds United will move ahead of Birmingham if they beat Aston Villa in the evening kickoff.
Blackburn Rovers drew at home to Huddersfield Town to keep out of the bottom three, but Rotherham United and Wigan Athletic both lost to fall further behind their relegation rivals.
A goal in each half enabled mid-table Bristol City to beat Ipswich Town 2-0 and move to within three points of the playoff places.
(Reporting by Neville Dalton, editing by Neil Robinson)
