Stephen Dobbie's 76th-minute winner proved enough to send Swansea back into the automatic promotion places while Nottingham Forest suffered late woe on a dramatic night of npower Championship action.
Starting the evening in second place, Forest recovered from a poor start against rock-bottom Preston to snatch what they thought was a winner in injury time - only for visiting striker Billy Jones to head home an even later leveller.
Forest's 2-2 draw meant Dobbie's strike which sunk Coventry at the Ricoh Arena was enough to send the Swans back into second, behind Queen's Park Rangers who maintained their five-point lead with a 2-0 win over Ipswich.
Cardiff also leapfrogged Forest into third place as a goal in each half from Michael Chopra and Aaron Ramsey proved enough to see off Sven Goran Eriksson's Leicester, who remain just outside the play-off zone.
It could have been worse for Forest if Norwich had hung onto an early lead to take the points against Doncaster. Grant Holt opened the scoring after 31 minutes but Rovers grabbed a 1-1 draw when Adam Drury put through his own goal seven minutes from time.
Leeds also failed to make the most of their opportunity as they twice blew the lead against Barnsley at Elland Road and eventually had to settle for a point in an exciting 3-3 draw.
Luciano Becchio and Max Gradel had cancelled out Jason Shackell's early opener but Matthew Hill equalised for Barnsley early in the second half and Leeds had Bradley Johnson sent off on 52 for a second booking. Leeds went back in front through Gradel's second on 70 minutes, only for Mark Robins' men to grab their leveller from a Kieran Trippier free-kick.
Anthony Gerrard's 71st-minute winner maintained Hull's slim play-off hopes with a 1-0 win at Derby, while Reading also retained a hope after Nicky Hunt and Shane Long scored in a 2-1 win over fading Millwall.
At the bottom, Scunthorpe boosted their survival hopes in dramatic fashion as they came from behind to snatch a 3-2 win over fellow strugglers Sheffield United at Glanford Park.
Crystal Palace are the team left looking anxiously over their shoulders at the drop zone after they slid to a 1-0 defeat to Portsmouth at Fratton Park, while Bristol City went a long way towards extinguishing their own relegation fears with a surprise 3-1 win at Watford. The visitors came from behind with goals from Nicky Maynard, Marvin Elliott and Brett Pitman.
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