The silence trackside at Celtic Park yesterday was broken only by the clicking of photographers' cameras and the polite instructions called out from the small group of snappers.

But Gary Mackay-Steven and Stuart Armstrong know only too well how the stadium can creak and bounce under the bright lights.

And for both players, the prospect of the pressure, the intensity, the clamour for success and the exposure that playing for Celtic brings, was instrumental in getting them into Ronny Deila's side in a last-gasp transfer swoop on Monday night.

United were left reeling at the loss of the duo while Celtic, by contrast, were thrilled to have added two players who they believe will be significant in their push for a domestic Treble this season.

And while neither will be eligible for next month's League Cup final meeting at Hampden against their former team, they were keen to adopt the long-term view of what silverware they can enjoy by taking up a place at Celtic Park.

"We want to come and challenge against the best and, ultimately, become better players," said Mackay-Steven. "Training with the calibre of player that is here will raise our game.

"I would like to improve every aspect of my game. I want to chip in with goals and assists. You'll never be the perfect player, but I want to work hard and be the best that I can be.

"When a club like Celtic shows interest, your head is immediately turned. The facilities, the stature of the club; it is world renowned. It is an unbelievable arena to play football in. We want to kick on with our careers.

"There are massive games against Inter Milan and nothing too much has to be said about that, given how exciting that is for everyone. They play football the right way here. The manager has them playing them on the ground and that is what we like. We want to attack and be easy on the eye. They do that here. It is what Celtic are known for here."

And Armstrong, who made 150 appearances for the Tangerines and netted 22 goals, was of a similar mind. Compared to Thomas Muller by Deila and talked up by Scott Brown, he is keen to get in and get started.

"The League Cup final will be quite a strange one for me," said the midfielder. "It was difficult to leave United given the people I had met along the way and also Jackie McNamara.

"I had a lot of friends and long-lasting relationships because five-and-a-half years is a long time. But I think the opportunity to come to Celtic and further my career by winning silverware is fantastic for me."

While McNamara was undoubtedly disappointed to lose two of his most influential performers, he was nevertheless happy to dole out some advice.

Having been at Celtic as a player through the barren, difficult years as well as the success-laden ones under Martin O'Neill, the former Scotland internationalist was well placed to provide an insight into the difference that the players can expect to deal with.

And Armstrong believes his game has improved under the tutelage of McNamara, who gave him the freedom to make mistakes and to learn from them.

"He was of the opinion that, if it was the right thing for me, it would be a good thing to do," said Armstrong, who spent last night cramming his way through a 2000-word employment law essay for his Open University degree course.

"He was good with me and I have a lot of respect for Jackie. I wouldn't say he actively encouraged me to go, but his sole focus was on whether I would be happy and whether or not it would be good for my career.

"He's been huge in my development, with the freedom he gives his boys to play. As an attacking player, it's been very important to me.

"He lets you make mistakes and he'll never criticise for you making a mistake when you are trying to make an attacking move.

"That's very important to have that creativity and it reeds confidence. His mentality towards the game is terrific."

The move to Celtic wasn't definite until late evening on Monday, but Armstrong has maintained that he was keen to make the move as soon as he learned of the concrete interest from the Parkhead side.

There were suggestions that his preferred move would have been to England and, although he has acknowledged that he would like to play his football south of the border in the future, he is adamant that the challenges provided in Glasgow will be sufficient for now.

"I think every player has ambitions there, but I never said England was my sole target," he said.

"I think it became apparent Celtic were very interested and, when a team shows that level of interest and follows up that interest, it is very flattering. A massive club like this doing that is very hard to turn down."

Neither player will feature against Dundee at Dens Park on Saturday afternoon since they are both cup-tied - Armstrong joked that the duo had been abused enough at the ground - but they are expected to be integral parts of Deila's side.

Neither, though, would take that for granted.

"I wouldn't say I am going straight into the first team," reflected Armstrong. " Everyone has to work hard to prove themselves and show that they deserve to be out on the park.

"It is a different kind of football. It is an enormous club and there will be a big difference to what we are used to but I am really looking forward to it. It is another step in my career."