Preston 0 Portsmouth 1:David James continued his outstanding form with a second-half penalty save before Preston midfielder Darren Carter scored a 93rd-minute own-goal to fortuitously guide Portsmouth into the FA Cup quarter-finals.
North End lie fourth bottom in the Coca-Cola Championship but they belied their lowly status with a vibrant display and the award of a 60th-minute spot-kick put them on course for a famous victory.
But James flung his 6ft 5in frame to his right to deny Preston midfielder Simon Whaley from 12 yards and Carter compounded the misery among home supporters when he fired the ball into his own net.
James continued to excel and did superbly well to get a hand to Brown's long-range strike and then did likewise to repel a 20-yard piledriver from Mellor.
Preston continued to pile on the pressure but Pompey stole victory from a corner in injury-time when Carter was unlucky to get the last touch to a goalmouth scramble.
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