"The script and the headlines were both written this morning," a rueful Gregory said afterwards. "But I don't have any regrets about the decision I made about Keane. Without doubt he has done well for Coventry, but I prefer to reserve my judgement until he's had a whole season."
Gregory, who has spent pounds 35m on players during his rollercoaster 20-month reign, was not prepared to go beyond pounds 5m for the 19-year-old Dubliner. Gordon Strachan did meet Wolves' pounds 6m asking price and Keane has inspired his new club to a surge up the Premiership table - they are now top of the bottom half - while Villa are drifting in the opposite direction.
By stopping Villa's run of six successive victories at Highfield Road, Coventry extended their own unbeaten sequence to seven games. Gregory's task is to halt an identical run without a win, which now stretches more than two months. Malicious whispers say that the axe wielded so often in the past by "Deadly" Doug Ellis, the Villa chairman, may fall again before he has a chance to do so, and the home crowd crowed: "You're getting sacked in the morning" in the final minutes.
While Coventry undoubtedly deserved their success, Gregory could reasonably point to the disproportionate amount of bad luck Villa suffered. They had a cast-iron claim for a penalty rejected after only six minutes, and, as if to rub in the discomfort for the Sky Blues' illustrious neighbours, Keane was clearly offside when he capped a virtuoso display with his 65th- minute winner.
Gregory's job security was by no means the only sub-plot adding spice to the occasion. There is no love lost between Ellis and Coventry's chairman, Bryan Richardson, the antipathy stemming from the defection of Dion Dublin and George Boateng to Villa and being further fuelled by their mutual interest in Keane.
Unsurprisingly, given such a background, the atmosphere was highly charged. Villa, whose followers had taken up only half the club's allocation of 4,000 tickets, twice came close to silencing their detractors in the opening minutes, their first opportunity directly involving both targets of the Coventry supporters' "Judas" taunts.
Boateng began the attack with a sweeping pass wide to Mark Delaney. Dublin met his centre with a sharp downward header which reared up off the turf and flashed over the bar. Almost immediately, Paul Telfer's back-pass was seized on by Julian Joachim, whose tumble under Paul Williams' illegal challenge left the referee, Graham Barber, strangely unmoved.
None of the Villa contingent seemed up for any reciprocal booing of Keane, perhaps because their hearts were in their mouths whenever he was on the ball. After only eight minutes, he took Youssef Chippo's pass and jigged past Delaney on the byline before crossing. A glancing header gave Cedric Roussel his first goal since arriving on loan from Ghent.
David James' full-length save kept out Moustapha Hadji's 25-yard drive as Coventry dominated the first half, while an even better, if less dramatic, block by the Villa keeper turned Keane's shot on to a post. Alan Wright cleared, and the upturn in the visitors' fortunes continued in the 41st minute when Dublin rose unchallenged to head in Steve Stone's corner.
For a time, Villa no longer resembled an embarrassment waiting to happen, their challenges becoming fierce where they had earlier been tentative. Lee Hendrie had been the only player cautioned in the first half, and for dissent at that. Yet a spate of heavy fouls after the interval led to the referee adding the names of Villa's Ian Taylor and Boateng either side of a yellow card for Paul Telfer.
Boateng's offence was to cut Keane down in full flight, but Coventry's new cult hero did not have to wait long for the sweetest revenge. Chippo, feeding the ball in from the left, saw Keane steer his pass deftly past James. Keane was offside, but the fact that this escaped the notice of the officials summed up both his and Villa's fortunes right now.
Coventry City (4-4-2): Hedman; Telfer, Breen, Williams, Hall; Hadji, Palmer, McAllister, Chippo (Burrows, 89); Keane, Roussel (Whelan, 88). Substitutes not used: Konjic, Eustace, Ogrizovic (gk).
Aston Villa (4-4-2): James; Delaney (Watson, 75), Calderwood, Southgate, Wright; Stone, Boateng, Taylor, Hendrie; Joachim (Vassell, 75), Dublin. Substitutes not used: Merson, Carbone, Enckleman (gk).
Referee: G Barber (Tring).