The Blades are still without a Sky Bet League One point after suffering a second consecutive defeat on Saturday.
A 78th minute goal, dubiously credited as an own goal, was the difference between Coventry and the Blades at Sixfields Stadium.
Pre-match stats showed both teams had previously beaten the other 19 times with 19 draws - the own goal ended the equilibrium!
Despite the midweek Capital One Cup win, boss Clough reverted to the XI that started the campaign opener against Bristol City. New signings McEveley and Turner were added to the bench in place of Porter and Willis, whilst Coventry's squad list included ex-Blade Miller amongst their substitutes.
Davies was the most prominent individual of the first 20 minutes, whipping in a number of inviting crosses, including one on 16 minutes which Higdon powerfully met but goalkeeper Allsop made a fine reaction save. Davies also had a free-kick blocked after Johnson was adjudged to have fouled Higdon on the edge of the box.
Early on Coventry seemed content to play on the counter attack and took 27 minutes to get in the Blades box but Alcock blocked from Swanson. A 25-yard free-kick from O'Brien was then on target but comfortable for Howard and Basham was the first to be shown a yellow card for two fouls in quick succession.
On 36 minutes Howard was called upon to make a full length save from Swanson but Coventry were in the ascendancy as half-time approached. Johnson's free header from a corner was ushered wide and Clarke met a Haynes cross but was unable to find the target.
With Coventry on the front foot, Clough would have been the happier of the two managers to hear the half-time whistle to reiterate his messages to his players. Neither side made a change at the interval.
Chances were in short supply at both ends early in the second half and Tudgay opted to cross when in a position to shoot, which frustrated the Coventry fans.
Clough made amendments just after the hour, a double change seeing McEveley and Baxter taking over from Flynn and Scougall. Coventry followed suit and Miller was introduced, quickly drawing a foul from Harris, the left-back getting booked, before O'Brien's free-kick floated into the hands of Howard.
Tudgay fired wide, under pressure from Alcock, after Davies was robbed on the halfway line and United's final change was to bring on former Coventry skipper Doyle for the tiring Reed.
A shot from Willis, after cutting in from the right, was easy for Howard but the goalkeeper was beaten on 78 minutes. A cross from the left saw O'Brien involved but the 'goal' was recorded as a HARRIS own goal with the defender in close proximity.
United's next attack saw Murphy sidefoot the ball home but the flag had already been raised for offside and with five minutes to go Basham beat goalkeeper Allsop in the air from a Harris free-kick but the midfielder was unable to force the ball home.
Late on United struggled to make inroads, a dangerous Davies free-kick was cleared, and the final whistle soon followed, which left 931 Blades inside the Sixfields Stadium unhappy.
Coventry: Allsop, Willis, Webster, Johnson, Fleck (Thomas 84), McQuoid (Miller 62), Swanson (Daniels 75), O'Brien, Tudgay, Clarke, Haynes.
Unused: Burge, Coulibaly, Phillips, Finch.
Blades: Howard, Alcock, Harris, Basham, Flynn (McEveley 61), Murphy, Scougall (Baxter 61), Davies, McGahey, Higdon, Reed (Doyle 71).
Unused: McNulty, Collins, Campbell-Ryce, Turner.