Boyata, Ronny Deila’s major signing ahead of the new season, knew nothing of the former Dundee United winger before he joined the club from Manchester City.
But now the talented centre back tries to avoid him in training in case Mackay-Steven makes him look foolish.
The 24-year-old, who cost around £1.5million, knows that one piece of individual skill could make the difference as Celtic attempt to negotiate three qualifying ties, starting with Icelandic outfit Stjarnan.
He feels Mackay-Steven reminds him of his former Etihad Stadium team-mate David Silva and knows he can be a game-changer.
Boyata said: “Wingers like that, who are quick, can take people on and can score goals, are a real plus for the game. You always need the special players that can do something that the other players can’t.
“He is a really good prospect. I didn’t know him from before but now I know all about him.
“I haven’t played in a one-v-one against him but he looks really sharp and if I see him running at me very quickly I think I will just jog back!
“I am not the player who is going to take the player on one versus one to score the goal but Gary is like that just like Silva.
“I am a defender and if we play well then the score will still be 0-0 but if GMS plays well it could be three or 4-0.
“Of course, he could the key in our Champions League matches but, when you talk about the team, you should be talking about everyone.”
Boyata strolled through his first appearance on Wednesday night when Mackay-Steven was the outstanding performer in the 2-0 win over Dutch side Den Bosch.
The centre-back will be back in action at St Mirren Park today when Celtic play their second warm-up game against Dukla Prague, a club who hold a place in Celtic’s history as they were defeated in the semi-final of the European Cup in 1967.
He was partnered by Virgil van Dijk in the Den Bosch game and he hopes they will be a fixture in the season ahead, even if the Dutchman has made his wishes known about moving to the Barclays Premier League.
He said: “You never know who you are going to play with but Virgil is a really good player and we all know that.
“I don’t know what is going on with Virgil.
“I can’t say what is going to happen in the future.
“I found it really good with him on Wednesday and, hopefully, that will continue to be the case.”
“I like the way we play and I think it really suits me. You always want to show the best you can and the Den Bosch game was our first one back.
“We will try bit after bit to show our qualities and that will come after we get our fitness back.”
Boyata is set to be joined in defence today by Saidy Janko, who officially signed yesterday from the red half of Manchester, and he is looking forward to having the Swiss teenager as a team-mate.
The two did not cross swords in a Manchester derby but he is aware of Janko’s abilities.
He said: “I didn’t play against him but I have seen him play against City. He is a good player. He is a forward thinking player.
“He is a full back but he likes to get forward and to attack and put a lot of crosses in.”
Janko has arrived as Adam Mathews concluded his move to Sunderland after Celtic accepted a bid reported to be around £2 million. The 23-year-old Welsh internationalist completed an agreement on personal terms yesterday evening to join the Wear-siders, who escaped relegation last season under ex-Rangers boss Dick Advocaat.
Matthews made 148 appearances for Celtic and won four consecutive titles.