Thomas Gravesen has warned Copenhagen they need a result tomorrow night before they face the "inferno" of Celtic Park.
The Danish side host Celtic in the first leg of their Europa League last 32 clash, having sold top-scorer Pieros Sotiriou.
Neil Lennon's side topped a group including Rennes, Cluj and Serie A title challengers Lazio, and have won every game in 2020.
Gravesen made 29 appearances for the Hoops in the 2006-07 season, and the Dane offered advice to Copenhagen.
He told the club's website: "Copenhagen have to be ready from the start, it's a hugely important battle and it starts right here in the Parken.
"You can't give anything away here but at the same time you have to be positive and try to dominate to see if you can get a result to bring to Celtic Park.
"When you get to Celtic Park, Celtic know how to use it and how much pressure to put on.
"If the fans feel only one goal is needed the sound level rises and you have to be ready to experience an inferno."
