Daniel Jebbison's late goal reduced Coventry's Sky Bet Championship lead to five points after a resilient 10-man Preston team frustrated the league leaders in a 1-1 draw.
Jebbison seriously dashed Coventry's advantage with his prodded finish 14 minutes from time.
Until the Canadian's equaliser, Coventry were in complete control, with the help of Liam Lindsay's red card for dragging back Haji Wright, and took the lead after Andrew Hughes' deflected a shot into his own net.
For large parts of the first half, Wright was the only threat for either side, and almost everything he attempted was managed well by Preston.
The American was found hurrying behind Preston's defence and, after his touch shifted him wide, it allowed Daniel Iversen to deny him.
The Lancashire club were forced to defend for the majority of the half, but did look threatening in the rare flurry forward. Lewis Dobbin turned into space but floated his shot just over the bar.
It was only seven minutes after Wright's first effort that he was found in a similar position.
This time he wrestled past his opponent before unleashing a shot that Preston's goalkeeper flicked round a post magnificently.
As half-time approached, he fired a header over from close range, but with six minutes until the break he was rushing behind Preston's defence before being dragged to the ground by Lindsay, who saw red for the challenge.
With the man advantage, Coventry's pressure intensified, with Wright prodding a shot that Iversen thwarted again three minutes into the second half.
And when the Championship leaders did break through Preston's defence in the second half, poor finishing let them down with Victor Torp scuffing his shot from just inside the box.
Preston suffered for almost all the game but, 15 minutes after the break, Harrison Armstrong hit a looping volley over his head that forced Carl Rushworth into tapping it over the bar.
But that was a rare test for Coventry's defence, as Iversen was again called into action and again responded heroically, diving across goal to parry away Torp's close-ranged effort.
After 70 minutes, Coventry finally found their breakthrough via a huge stroke of luck. Rudoni collected the ball and hit a shot that heavily deflected off Hughes to wrongfoot Iversen and rolled in.
Instead of kicking on from the goal, they were pegged back six minutes later when Jebbison poked Pol Valentin's cross past Rushworth to dent their lead at the top of the Championship and keep Preston two points into the play-off positions.
Preston's Paul Heckingbottom:
"We have been resilient all season, but I felt that when they scored we were the ones that looked more threatening.
"They were going for it in the final couple of minutes, but everyone to a man was really committed to getting the point that we needed.
"The sending-off sort of zoned us in, because we knew what we had to do to win the game.
"I think nothing really changed in principle throughout the game, the principles are the same. We just needed to make a problem in their box and it worked really well for us.
"I felt we were really positives at time, and the changes we made gave us a real lift at times.
"This league is going to be crazy this season, it always is but this season more than any is going to be.
"I think today shows that we have gone up a place with a point. A point normally gets you nowhere but today was more than that point.
"We showed what we are really about, the determination and the spirit against a really good side and we got what we deserved."
Coventry's Frank Lampard:
"I am the first one to say that when we were 10 points clear and people don't go 10 points clear in December and win this league.
"There is a lot to be done and it is important that the players stay level-headed and it is one game in which we played pretty well, and one moment was costly.
"I said to the players it shouldn't feel like a loss but it does because of the standards and the way that we play.
"We clearly should have won the game. We are all frustrated, but we need to keep a level head in the context of the whole season.
"We never felt a threat against a team that have been getting results this season, it is frustrating against 10 men and if we scored the goals we should have done today and it is frustrating in the way we conceded."
