Ronny Deila believes that Stuart Armstrong and Gary Mackay-Steven will prove pivotal to Celtic as they head into the Uefa Champions League qualifiers later this summer.

And the Hoops manager is convinced that bringing both players in on the final night of the January transfer window could prove to be one of the most significant pieces of business that Celtic will conduct this year.

The pair settled quickly into the club, assimilating themselves with ease. It was not only in the SPFL that they took their chance, but also in the Europa League as Celtic went down to Inter Milan.

Deila will be in the transfer market over the next few weeks as he seeks a defender and a striker, but maintaining the current nucleus of his squad is what he regards as his priority over the coming weeks.

He will have to fight off interest in Virgil van Dijk and Stefan Johansen, but he is certain that, as his squad currently stands, Celtic are good enough to qualify for the group stage of Europe's premier competition.

"You can see how well both Stuart and Gary have played since they came here, which is important," said Deila.

"They are young, hungry Scottish players who know the game here and know the league and we expected that they would fit in very well.

"But they have been really excellent. You could see how well Stuart did on Sunday to set up Scott Brown's goal.

"He used his strength, he was very quick and it was a good cut-back.

"It was vital for me that we brought them in early rather than wait until this summer. It is not just about what they do on the pitch but also how much they have brought off it too.

"They both have a very good attitude, they have settled very quickly and they have also helped with competition every day here.

"They will be big players for us next season, I am sure of that. They have had a taste of European football by playing against Inter Milan in the Europa League and they will have an important part to play as we try to get into the group stage of the Uefa Champions League now."

While Deila has had much reason to re-live last year's disastrous qualifying games when Celtic were defeated by Legia Warsaw and then Maribor after the Poles had been found guilty of fielding an ineligible player, he believes that he is a better manager for experiencing those dark, early days in Glasgow.

Such was the difficult start that many predicted he would no longer be around by the end of the campaign, let alone be preparing to lead another assault on the competition. But it is not just Deila who feels as though he is in a far better place as Celtic look to close in on a place in the group stage.

The Hoops boss has pointed to the greater cohesion and fluency within his side and the fact they acquitted themselves well in the Europa League also points to some kind of improvement.

Yet the real proof of just how far Celtic have come since last year will be effectively measured when they begin their quest to make it into the Champions League.

"Our goal now is the group stage," said Deila. "We are much more prepared than we were last year but the Europa League was good for us because we got more experience and had two good games against Inter Milan. That can help us in the Champions League. I have experienced a lot of tough times on the football pitch as a player and as a manager.

"If you are a good manager then you learn from the bad things and take with you the positive things and develop.

"I have experienced it. I know how to fail. But I have my thoughts on how we can do it right now."

Celtic play again on Friday night when they take on St Johnstone in Perth and Deila will look to change things slightly.

It is believed that he will offer certain senior players at the club the chance to take a breather after the demands of the season, although he remains insistent that he wants to make it to the end of the season without dropping any points.

"We might rest a few players, we will see," he said. "But the most important thing is that we try to keep going. It will be another big game on Friday night before we get the trophy next week.

"It has been a great season from everyone and it is the players who deserve the most credit. They have been excellent and since Christmas I think you can see how we got better - we have been really consistent.

"We want to keep dominating Scottish football now but we know that we have to achieve that while also showing that we can live with the best in Europe.

"That is the challenge."