After a run of two wins in nine games saw Frank Lampard's men blow a comfortable advantage in the race for promotion to the Premier League, Coventry have bounced back with three consecutive wins.
Sheffield United also needed a win to remain on the fringes of the fight for a place in the play-offs and led just after half-time through Harrison Burrows.
But two goals in five minutes from Haji Wright and Jack Rudoni turned the game around to edge the Sky Blues closer to a return to the English top flight for the first time in 25 years.
Millwall closed to within four points of second-placed Middlesbrough with a comprehensive win over play-off hopefuls Birmingham.
Goals from Femi Azeez, Tristan Crama and Jake Cooper put the Lions well on course for the three points before Birmingham's Jhon Solis was sent off.
Birmingham slip to 10th, five points outside the top six.
Norwich inflicted more pain on already-relegated Sheffield Wednesday with a 2-0 win at Carrow Road to climb eight points clear of the drop zone.