FULL-TIME: Coventry City 2 Scunthorpe United 1
But they came desperately close to snatching a point, with Gary Hooper denied from the penalty spot by Keiren Westwood and Paul Hayes having a last-minute effort ruled out for offside.
Having dominated the first-half, squandering several opportunities in the process, City took a deserved 55th-minute lead through on-loan striker Jon Stead.
But United were handed an ideal opportunity to hit back within four minutes when Hooper was brought down in the box by Leon Barnett, who received a second yellow card and was dismissed.
The Iron striker's hopes of an equaliser though were dashed by Westwood, who dived to his right to push away the penalty.
It was a miss after which United were punished, Sammy Clingan curling home an excellent 68th-minute free-kick from the edge of the box to double the home side's advantage.
Grant McCann came off the bench to give the Iron hope with a goal in the 83rd minute, but the strike was little more than a consolation.
United boss Nigel Adkins had made just one change to the side that drew 1-1 with Ipswich Town in midweek for the trip to Warwickshire.
Josh Wright returned to the starting XI in place of Garry Thompson, who dropped to the bench.
The former Charlton man partnered Sam Togwell in the centre of the park, with Matt Sparrow playing wide right.
Coventry, looking for their sixth win in their last seven home matches, brought in on-loan West Brom centre-back Barnett for the injured Richard Wood in the middle of their defence.
Both teams struggled to make any attacking progress in the opening stages and it wasn't until the 29th minute that the game's first effort on goal arrived.
Given that the ball had spent the majority of time in the Iron half, it was no surprise that it came for the Sky Blues.
Midfielder Aron Gunarsson fired an excellent 30-yard drive towards the top right-hand corner of Joe Murphy's goal, but the Irishman reacted superbly to tip the ball over for a corner.
The Icelandic international had another golden chance two minutes later, dashing through the middle of the field as the Iron defence parted like the Red Sea before Moses, but could only pull his shot wide.
The closest United came to scoring in a tepid opening 45 minutes was when Togwell poked wide when rushing onto a Hooper through ball into the City box.
The second half was, however, a very different affair.
Almost straight from the kick-off Hooper streaked clean through. Barnett slid across the 13-goal striker in the City box and took both ball and man, leaving referee Paul Taylor with a big call to make - particularly as he was more than 50 yards away from the incident.
Yet despite calls for a penalty from the visiting players and fans, the Hertfordshire official awarded nothing - letting Coventry off the hook.
It was a sign of what was to come as the game exploded into life.
Ten minutes after the restart, in what proved the start of a mad five minutes, Stead found space on the edge of the Iron box to fire low shot through a crowded penalty area and into the net.
Then, Hooper was brought down by Barnett, with Taylor this time penalising the defender with a second yellow card and pointing to the spot.
Protests from the Sky Blues' players meant Hooper had to wait an age before being allowed to rest the ball on the penalty spot, and the Iron striker looked to the sky in disbelief when Westwood beat his low effort away and Paul Hayes flicked the rebound across the face of goal and wide.
Within 10 minutes of going to 10 men, the home side made United pay for their miss, doubling their lead courtesy of the impressive Clingan's superb set-piece.
Having brought on Garry Thompson and Donal McDermott to give them more width, Scunthorpe did eventually get some luck in front of goal.
The former of that duo whipped in a low left-footed cross and McCann lashed home from inside the area to give his side hope of an unlikely point.
That was exactly what they thought had happened with less than 60 seconds remaining when a thumping drive from Thompson looped into the net off Hayes, but the goal was disallowed for offside.
Really though, a share of the spoils would have been undeserved for United, as the Sky Blues played out five minutes of added time without too many problems.
TEAMS
COVENTRY: Westwood; Wright, McPake, Barnett, Cranie; Baker, Clingan, Gunnarsson, McIndoe; Morrison (Eastwood 86), Stead (Deegan 81). Subs not used: Konstantopolous (GK), Hussey, Sears, Turner, Grandison.
SCUNTHORPE: Murphy; Byrne, Mirfin, Raynes, Williams; Sparrow (McCann 71), J Wright, Togwell (Thompson 64), Woolford (McDermott 64); Hayes, Hooper. Subs not used: Lillis (GK), Milne, Canavan, Forte.
ATTENDENCE: 16,197 (489 away).
Comment on this story