Sky Bet Championship strugglers Stoke eased their relegation worries with a battling 2-0 home win over play-off chasers Cardiff.
Victory for Stoke was their first at home in the league against Cardiff since February 2008, with O'Neill's charges having pulled further away from the relegation zone with a much-needed three points.
Northern Irishman O'Neill refused to make any changes to his side despite successive defeats in their last two league outings.
The hosts proved the brighter out of the blocks and striker Campbell was denied a sixth-minute opener after a smart point-blank block by Smithies.
Winger Sam Clucas provided an inch-perfect pass for Campbell to latch on to, but an alert Smithies raced off his line to avert the danger.
Cardiff countered and – at the other end – Ward shot straight at Stoke goalkeeper Jack Butland with their first chance of the contest.
Tom Ince lost his marker with some trickery but rifled just wide with a powerful left-footed shot for the hosts soon after.
But then the breakthrough came in fortuitous circumstances for O'Neill's side.
Jordan Thompson's inswinging corner from the right wing evaded everyone but Paterson who, unluckily, saw the ball cannon off his back and into the empty net.
It was an unfortunate way to go a goal behind, but Stoke were not complaining.
Campbell had an excellent chance to double the lead shortly after the half-hour mark, but his shot from close to the penalty spot was deflected wide.
Stoke could have extended their lead 15 seconds after the resumption, but Nick Powell lashed into the side netting with a stinging strike.
Campbell curled a left-footed shot inches wide before proving a nuisance for the second goal. Smithies did well to twice thwart him, but Wales international Allen pounced to seal the points.
Campbell so nearly scored after a superb solo run, but Smithies tipped his fizzing strike wide of his left post.
But the Bluebirds lacked a killer finish and the Potters claimed only their second win in five games to boost their survival hopes as they sit three points above the drop zone.