The Danish club, in the group stages for the first time since 1995, are fourth seeds in a section that also contains holders Manchester United and Spanish side Villarreal.

Aalborg's players had their first experience of the stadium when they had the traditional pre-game training session on the rain-soaked Parkhead turf.

However, the former Scotland captain, who himself is experiencing his first taste of the group stages of the competition at the age of 61, knows it will all be different at kick-off time.

"There are so many factors that we don't know at the moment," the former Bolton, Arsenal and Middlesbrough boss said.

"For most of my players it will be a once-in-a-lifetime opportunity. We are in an incredible group and for most of our players the opportunity to come to Celtic Park and Old Trafford may never happen again.

"Celtic Park is a magnificent stadium, it is a theatre. The fan-base here is phenomenal and there will be great support at the game.

"The players have got to take in the environment in which they trained, take in the size and status of the stadium.

"We can only find out what will happen when we get the players out there for the game.

"I have a lot of confidence in the players in terms of their character and personality, they've had some good performances in the UEFA Cup last year but the Champions League is unique and special.

"The stadium is dressed up differently, there is a different atmosphere in the stadium and everything is done differently in terms of preparation in the Champions League.

"You hope you have a group of players that can go out and perform. We have to feel confident and that's why we are here, we are part of the group.

"I am really excited about this draw and the games we have to play."

Rioch insists his players have already reached their goal this season.

"Our aim was to get into the group stages which is a magnificent achievement by the players," he said.

"But we will come and play football and be as competitive as we can.

"You cannot predict football but we understand it will be tough."

Rioch has no bitterness about making his debut in club football's premier club competition at so late a stage in his career.

He said: "Football has been fantastic for me.

"I started at 15 and I have had only one job - football.

"I was a player for 25 years and coach for 20-plus years and I owe everything that I have to football.

"It is fantastic and four months ago I didn't think I would get the chance to be involved in the Champions League.

"I got the chance with Aalborg and so I am really excited."

Defender Kasper Bogelund has been ruled out of the match with a hamstring injury.