Henrik Larsson says it will be tough for him to support either side when Celtic host Barcelona in the Champions League on Wednesday.
Larsson won multiple Scottish Premier League titles with Celtic while claiming the Champions League with Barcelona in 2006.
The Swede feels Celtic can take heart from last month's performance against the Catalan giants, when the Scottish giants lost 2-1 following Jordi Alba's 94th minute strike.
"It's hard for me because I had some great moments at Barcelona where I won the Champions League and everything so I still have some feelings for both of the clubs," Larsson said.
"But Celtic were the underdogs in that game and I think they have done themselves really proud and I think it's important not only for themselves but for the Scottish game."
Larsson believes Neil Lennon's men must use the atmosphere at Celtic Park to help them intimidate and disrupt Barca's fluid passing game.
"You can't really attack them that much, you have to defend and I thought they had a really, really good game," he said.
"Unfortunately, they didn't manage to hold on for the draw because it would have been an excellent result away from home.
"It's going to be noisy, you are not going to be able to speak to each other. As soon as a Celtic player has the ball at his feet, there's going to be a great roar.
"When they do the huddle, it's going to be something special, even for the players of Barcelona."