The champions were knocked off the summit of the Premiership by Aberdeen at Pittodrie on Saturday and will find themselves five points behind their domestic title rivals if the Dons defeat Hamilton Accies in their game in hand tomorrow night.
The 2-1 loss to Derek McInnes’s side was a fresh setback for Celtic after their failure to reach the group stage of the Champions League when they lost to Malmö in the play-off round at the end of last month.
Ronny Deila and his squad are suddenly under intense scrutiny as they prepare for what appears a daunting Europa League Group A opener against Dutch League leaders Ajax at the Amsterdam ArenA on Thursday night.
But Mackay-Steven insists Celtic remain confident they can rise to the challenges now facing them on both the domestic and European fronts this season.
“It’s not a crisis in our eyes, to be honest,” said the winger. “It is early on in the season. We just didn’t play as well as we could on Saturday. Aberdeen are a good team and they punished us. But I think we will put things right. I am confident [we will still be the best team over the course of the season], yeah.
“It is good we have got a massive game to look forward to on Thursday. We can put a lot of things right. It is never nice to lose, we are not used to losing. It is not the way the players approach the game. We have a winning mentality. Nobody accepts a loss. But they happen and we need to show what we are made of. So Ajax can’t come quickly enough.
“I think we have a point to prove, especially after the second leg against Malmö in the Champions League play-off. We didn’t feel that we played to the levels we can in that game, through one thing or another.
“So it is definitely a chance to showcase that we belong at that level. We need to prove it. We have done it before. There is no reason, if everyone is playing like we know they can, that we can’t go to Amsterdam and get a positive result. I am sure of it.”
Mackay-Steven revealed the Celtic dressing room was a scene of both anger and disappointment on Saturday after the dramatic nature of the defeat by Aberdeen.
Referee Craig Thomson was one target of Celtic’s ire for his decision only to book Aberdeen defender Andrew Considine for the foul on Leigh Griffiths in conceding the penalty from which the visitors took the lead.
Celtic were also upset by Thomson’s failure to take action against Dons midfielder Kenny McLean for a kick at Mikael Lustig while the Swedish defender was prostrate on the turf.
But Mackay-Steven admitted that most of Celtic’s frustration was reserved for their own failings, including another poorly conceded goal from a set piece for Aberdeen’s late winner.
“We are bitterly disappointed we let the three points go,” he said. “We were all pretty flat in there. We had it in our hands, definitely. In the second half we let it go, even with the extra man when Aberdeen had Jonny Hayes sent off. We didn’t make it count. That is the frustrating thing.
“Our penalty was a clear goalscoring chance and I don’t know how the ref thought it was a yellow card. We were 1-0 up and it is all ifs and buts. If we win the game, we don’t speak about it really. It is just one of those things.
“I think Mikael himself felt there was contact [from McLean] in that incident, but I didn’t speak to him after the game. At the time, it looked like that, but I didn’t see it myself.
“So we were a little bit angry at certain decisions, but that is part of the game. We were still in the driving seat and we didn’t make it count in the end.
“The manager was angry, but mainly at our performance. In the second half we didn’t create enough chances to win. Overall, Aberdeen deserved it, to be honest. He was just angry at our performance. I have seen it from him before at half-time in certain games and full-time in certain games where we haven’t done ourselves justice and this was one of those days.
“Losing the goal from the set piece was one of the things the manager was frustrated at. We have worked on it a lot. We will need to look at it on the video and eradicate any mistakes.
“We knew Aberdeen could challenge us this season. We know they’re our closest rivals. They showed in this game what a good team they are. They are going to be dangerous throughout the season. But we know ourselves what we can do. It is only one game and it is early in the season, but it is a big game.
“A lot of people will be thinking ‘Aberdeen will be riding high now’. We need to prove why we have been champions before. There are enough big characters in the dressing room to make sure this is just a one-off.”