Haji Wright scored twice as Coventry came from behind to beat Watford 2-1 at Vicarage Road.
The FA Cup quarter-finalists do not play another Championship fixture until March 29 and needed the three points to remain in the Championship play-off picture.
United States international Wright converted a 40th-minute penalty to cancel out Ryan Porteous’ headed opener and then struck a composed 72nd-minute winner from the edge of the area.
The defeat spelled the end of Valerien Ismael’s time in charge of the Hornets, who confirmed on Saturday night they had terminated the Frenchman’s contract and appointed Tom Cleverley as interim head coach.
The result was harsh on Watford, whose vibrant and energetic display belied their recent poor run of form.
Valerien Ismael’s side have now won just one of their past 10 league games and are in danger of being sucked into the increasingly-congested relegation battle.
Watford began positively, with an Edo Kayembe shot through the legs of a Coventry defender that was tipped away by the outstretched left hand of Brad Collins.
After Ismael Kone had pushed another effort just wide, the home side took the lead in straightforward fashion after 20 minutes.
A Ryan Andrews long throw found the head of Porteous, whose flick dropped over Collins and into the far corner.
At the other end, Wright took advantage of two Watford players running into each other, but he could only find the midriff of Watford goalkeeper Daniel Bachmann with his shot.
Having been outplayed for most of the half and looking disjointed, Coventry suddenly drew level.
Josh Eccles received a short pass from Ellis Simms before beating Porteous and then having his legs taken away by Bachmann, who had come rushing rashly out of his goal. Wright struck his spot-kick firmly into the corner.
The equaliser meant Watford extended their remarkable record of leading at half-time on just two occasions this season, the fewest of any club in England’s top four divisions.
With an FA Cup quarter-final at Wolves next weekend giving them a 20-day league hiatus, this felt like a match Mark Robins’ side needed to win.
Instead, it was Watford who continued to create the clearer opportunities, with another Kone shot followed by a Wesley Hoedt header that was held by Collins.
The Coventry keeper then stood firm at the near post to stop a strike from the impressive Yaser Asprilla.
But, just as they had in the opening period, Coventry conjured up a goal out of nothing.
Eccles played in Wright on the edge of the area and his shot was low and true into the bottom corner for his 13th league goal of the season.
Watford continued to press but lacked the ability to carve out any clear-cut openings before the final whistle that was greeted by boos from those home fans who remained inside Vicarage Road.