Pablo Counago fired a dramatic 97th-minute winner for Ipswich just 80 seconds after Richard Wood looked to have grabbed a 2-2 draw for in-form Coventry in a stunning finale at Portman Road.
It was nothing less than Town deserved but the nature of the winner left Sky Blues manager Chris Coleman fuming at the full-time whistle after referee Michael Oliver had signalled for a minimum of four minutes' stoppage time.
Clinton Morrison's well-taken strike handed the visitors a dream start after just two minutes but almost exclusively from that moment onwards it was the home side who dominated.
On-loan Crystal Palace marksman Stern John headed home his first goal for the Suffolk outfit just before the break to level matters, while fellow loanee Jack Colback was left unmarked to lash home in the 52nd minute.
Both sides threatened to add to the scoreline and Wood looked to have nicked a point with his stoppage-time header but substitute Counago stole the show even later when he struck from 12 yards.
It was the second time in the space of five days Coventry had been undone in added time after their FA Cup loss to Portsmouth, but it is now just one defeat in 14 league games for Ipswich after their awful start to the campaign.
Morrison scored both of City's goals in their 2-1 win over Ipswich on the opening day of the season and he again proved the scourge of Roy Keane's side after just 98 seconds.
The former Palace and Birmingham frontman was involved in a neat one-two with strike partner Freddy Eastwood before flicking a great finish into the top corner from around 20 yards.
But Town responded strongly and Damien Delaney was presented with a clear opportunity to level matters shortly after but he could only fire straight at highly-rated Sky Blues stopper Keiren Westwood.
Ipswich were really applying the pressure in search of an equaliser and were presented with a series of half chances - Liam Rosenior most notably seeing his goalbound effort deflected wide by team-mate Colback - while the visitors were also posing a threat on the counter-attack in an open, end-to-end first quarter.
Town's dominance continued as the first half wore on but, for all their pressing and attacking intent, Westwood had yet to be seriously troubled.
But all that changed in the 42nd minute as John grabbed a deserved equaliser with his first goal since he scored against Ipswich for Bristol City in December 2008.
Rosenior crossed from the right and John was on hand to head home and level matters, although he wasted a second good chance to fire Town in front just before half-time.
The second period continued in the same vein as the first, with most of the football being played in Coventry's half.
And it was no real surprise when Ipswich completed the turnaround seven minutes after the restart.
Another well-worked move down the right ended with Grant Leadbitter squaring for Colback in the area and he found himself in acres of space before duly slotting home.
Gary Deegan, making his Coventry debut after his switch from Bohemians, tested Town keeper Arran Lee-Barrett with a stunning 30-yard volley before the home defence was called upon to scramble the resulting corner to safety.
Morrison was then denied by Lee-Barrett as the Sky Blues threatened but it was Ipswich who then went on the offensive in search of a killer third.
Colback and Connor Wickham both forced saves from Westwood before Martin Cranie made a goal-line clearance to deny Counago.
But the home crowd were left rubbing their eyes after the late drama left Coventry still without a win at Portman Road for 16 years.
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