The Foxes started the brighter of the two sides but, with Cardiff seeming impossible to break down and dangerous on the counter attack - there can be no doubt that many fans feared another long, frustrating night awaited.
The Foxes have suffered some incredible ill fortune in the first five Championship matches and so it was no suprise when Cardiff took an undeserved lead thanks to a freak goal from Lee Naylor just before half an hour of play.
The midfielder picked up the ball on the sideline, 35 yards from goal, looked up and sent a cross into the box. An eery silence smothered the Spion Kop as the ball flew wickedly into Carl Ikeme's top right hand corner.
Paolo Sousa's men didn't let their heads drop though and could easily have pulled level minutes later when the ever dangerous Lloyd Dyer cut inside from the left wing and smashed his shot low and hard across goal, only for Waghorn to send the ball inches wide.
After the interval Leicester continued to press for an equaliser and the visitors began to show signs of weakness at the back.
And their persistence was rewarded on the hour mark when some neat passing football was rounded off in style as Richie Wellens picked out Andy King who had stormed into the box to head home to level matters.
Things went from bad to worse for Cardiff just two minutes later when Richie Wellens again found Andy King, this time on the edge of the box. This time the Welshman smashed the ball superbly into Marshall's top right hand corner to send the Blue Army into ecstacy.
And, a rattled Marshall nearly handed the Foxes a two goal lead when his poorly taken goal kick fell to the feet of Lloyd Dyer. The winger advanced on goal but could only find the post when he should have put the Foxes out of sight.
Leicester held on for all three points and will now be full of confidence going into Saturday's home tie against Championship leaders QPR.