The midfielder's greatest claim to fame has been as a footnote in the epic story of Jack Charlton. If it had not been for Mackay, on one of his few Scotland appearances, then the Republic would never have reached their first major tournament and football, and bar owners, the world over would have been poorer.
Mackay's goal in Sofia in 1987 denied Bulgaria a place in the European Championship finals in Germany, an event which the Irish went on to captivate. Now, after all these years of being known for his favour to others, the 32-year-old would love to win something for the cause closest to his own heart in today's Coca-Cola Cup final.
Six months after the numbing humiliation of a 5-1 Scottish Cup final defeat at the hands of Rangers, Mackay and his team-mates are in another final. Their torturers confront them once again, but at least today's game at Parkhead provides Hearts with the earliest opportunity to erase a painful memory. What surprises Mackay is that he is there to take part again. "I was afraid the Scottish Cup final was going to be my last chance of a trophy," he confessed, "and maybe even my last game for the club.
"I was out of contract during the summer and being linked with other clubs. The manager, Jim Jefferies, wanted to freshen the club up and I had to accept the changes at Tynecastle or I knew I would fall by the wayside.
"I put in a lot of hard work during the summer with a sprint coach at Meadowbank and, given my age, I'm as fit as I can be. Certainly, it's had a benefit because my own form has been as good as ever."
Mackay, a Hearts fan in boyhood, has been with them for half his life, playing more than 500 first-team games. He embodies the club but, for some, he also embodies its shortcomings.
Mackay and his contemporary, the striker John Robertson, were seen by many critics as representing the failure - not a piece of silverware in 34 years - of Scotland's biggest club outside the Old Firm; nearly-men and not nearly good enough.
The stigma attached itself a decade ago after Hearts managed to let the double slip through their fingers in the space of a week. First the league title, just seven short minutes away on the final Saturday, was handed to Celtic; then, the following week , the Scottish Cup final was lost to Aberdeen.
After that, Hearts managed to lose five successive semi-finals, and when they did get past that hurdle last season, Rangers made them rue that they had.
"Once, all we ever heard was that semis were jinxed for us," Mackay said. "The pressure was too great because the club had gone so long without anything. However, that is something we have now overcome by reaching the final of successive tournaments. We don't feel there is any pressure at all on in this one."
Mackay also feels Hearts are better equipped than ever to land that elusive trophy thanks to Jefferies' shake-up, which has brought in the former Milan and Atalanta midfielder Stefano Salvatori, the French international striker Stephane Paille, who played with Bordeaux and Porto, and the former Norwich midfielder Jeremy Goss.
"The measure of a squad is how good the bench is and when you consider we have the likes of Jeremy and Pasquale Bruno there, that shows we are stronger now. If I had left Hearts in the summer and they had gone on to reach this final without me, I would have been envious. As a supporter I would have been glad, but I am as selfish as the next player. I want to win something."
And maybe a few glasses in Dublin will be raised in his honour if Mackay's cup finally overflows.Reuse content