Sunderland chief Steve Walton admits they'll have to adjust their transfer spending to fit into UEFA's new financial rules.
European football's governing body have introduced new measures limiting clubs to only spend what they earn and making sure they meet their financial obligations.
The rules will be implemented in phases during the next three years and are expected to be fully in place by 2012-13.
"It will affect all clubs who have ambitions to play in Europe," Walton, one of the game's top financial men, told safc.com.
"It really starts to bite in two years' time in terms of finances, so it would be a tragedy if we were to get into a position to play in Europe and then couldn't because of the Fair Play regulations.
"So it is massively important for us to make sure we can achieve that."