Manchester United are pursuing the Toffees duo, and are thought to be set to launch another bid to reunite them with former Goodison Park boss David Moyes.
With just a few days of the transfer window remaining, and a quick resolution needed as to whether Fellaini or Baines leave or not, Toffees boss Roberto Martinez will take his side to Cardiff City Stadium looking for their first win under his stewardship.
But Mackay does not believe the former Swansea manager, who can expect a hostile reception from the Bluebirds' faithful, will have been distracted by the furore over two of his key players.
He said: "I think every club at the moment is getting used to speculation around its players.
"We've had a lot of it concerning players we want to bring in.
"But I know Roberto Martinez really well and he will be totally professional and have his team focused on the game.
"There has been a lot of speculation surrounding his players, but I'm sure the professionalism of Roberto, his players and his coaching staff will mean all focus will be on us and not what surrounds his football club."
Cardiff, who will be without injured striker Andreas Cornelius, face the Merseysiders on the back of their stunning 3-2 triumph over Manchester City.
The win ranks as arguably the most famous in the club's history, but Mackay and defender Matthew Connolly both know they must move on and refocus.
He said: "It was a major shock for us to beat Manchester City, but it gives us belief that we can compete at this level.
"We realise what a tough game Everton will be, we know it wasn't a one-off cup final last week, it is part of a whole season and my focus is on consistency."
Full-back Connolly added: "We have got to look at the larger picture and it is time to move on now.
"I haven't seen much about Everton. We know they are a good team and it will be a really tough, physical game.
"We are not going to play like we did against Manchester City every week, even though we will try our best.
"But when you go up, if you get a result against any of the top four or six teams you have got to see it as a bonus, as the main thing is to beat the teams around you."
Mackay, who has broken the club transfer record three times this summer, remains hopeful of making at least one further addition to his squad, but remained tight-lipped after being linked with Heerenveen striker Alfred Finnbogason and Ecuador winger Jefferson Montero.
"I think it will be a busy final few days of the window," he said.
"I am still trying to bring in a player but I don't talk about players from other clubs."