Aron Gunnarsson's 20th-minute strike prevented Mackay from exacting any revenge on a club that sacked him in controversial fashion 14 months ago, with the bad blood between the Scot and Tan continuing to linger to this day.
The latter and his board of directors opted not to attend this contest in protest as the Malaysian businessman is understood to remain incensed with the Football Association's handling of the racism investigations involving both Wigan owner Dave Whelan - another absentee at the DW Stadium on Tuesday night - and Mackay,
Their seats were instead filled by local volunteers from the community trust and Wigan Youth Zone, and they witnessed another home loss for the hosts, who have not won on their own turf in six months and are running out of time to preserve their Sky Bet Championship status.
It was a solitary goal by Gunnarsson, one of the influential figures in the Bluebirds' Championship promotion campaign under Mackay, that heaped further misery on the Latics boss and left his side still nine points from safety with just 13 games remaining.
Wigan did have two goals disallowed for offside but, given the current predicament, Mackay's reputation in Lancashire is far lower than it is in south Wales.
In the early stages songs in support of Mackay came from the travelling fans as they elected to fondly remember a man who took them to a first top-flight promotion in 52 years.
Two of the debutants Mackay picked combined for Latics' opening chance too as Gaetan Bong's left-wing cross was nodded wide by former Liverpool and Stoke midfielder Jermaine Pennant.
At the other end, Harry Maguire's outstretched boot turned away a Kenwyne Jones cross but the Wigan defending was non-existent when the Bluebirds next ventured forward.
Midfielder Gunnarsson waltzed past three blue and white shirts before opening his body and calmly side-footing past Ali Al Habsi.
Eoin Doyle had a goal-bound effort blocked by Jason Pearce and the former Chesterfield striker also smashed a swerving half-volley into Al Habsi's hands as Cardiff pushed for a second.
But Wigan did not collapse and felt they should have been level at half-time when Bong's centre was flicked on by Marc-Antoine Fortune and headed home by James McClean, who was adjudged to have been offside.
McClean was in again early in the second half but was denied by a fantastic last-ditch sliding challenge from Bruno Ecuele Manga.
Fortune twisted and turned and fired over the top from a tight angle and Wigan again had a goal chalked off for offside when Emmerson Boyce's inviting cross was turned home by substitute Martyn Waghorn.
However, fortune is deserting Mackay at the minute, a fact which will be met with little sympathy by the stay-away Cardiff hierarchy.