His side could virtually assure their lofty spot with victory against seventh-place Hibernian today, a result which would put them seven points clear of the capital club, with a game in hand.
Mackay believes that a win might just be the spoonful of sugar which helps Tommy Wright's medicine go down; the St Johnstone manager is recovering from gall bladder surgery and has left Callum Davidson in charge of the team.
Mackay, who has been filling-in at left-back with Brian Easton injured, said: "We have punched well above our weight for the past three seasons and long may it continue. Every year you see and hear people tip which teams are going to make the top six. St Johnstone rarely feature on anybody's list.
"We are a such a small club that we don't register on anyone's radar and nobody thinks about us at all. It would be a fantastic achievement to clinch a top-six place for the third consecutive season."
Mackay also insisted that in Davidson, Wright had entrusted the club to a safe pair of hands.
"Callum commands tremendous respect from the players. The manager will have picked the team anyway and we will not be affected by anything that has happened."
Meanwhile, from the opponent's point of view, Michael Nelson of Hibs has not given up on pipping the Perth side to that sixth place.
"Everyone is aware of the importance of the game," he said. "If we do put in a performance and get a win then it puts a little bit of pressure on St Johnstone, especially after they lost last week to Ross County. The situation would still be very much in their hands. But all we can do is affect this game, so we have to make sure that's what we do and see how they react to it."
Nelson finds manager Terry Butcher's approach to picking the team refreshing. "He is not happy any time we get beat and he certainly lets the players and the media know about it," he said.
"If you lose a game then you leave yourself open to being left out the team, it's as simple as that."