UEFA have urged big spending clubs to keep their summer finances in order as tougher Financial Fair Play (FFP) rules continue to be enforced.
The governing body's General Secretary Gianni Infantino insists that, although the break-even rule will not be implemented until next season, UEFA will be closely looking at the books of all clubs across the continent before then.
Monaco, PSG and Manchester City have all spent big in the summer transfer window and Infantino insists they could come under sanctions if the recruitment results in significant annual losses.
"Big clubs as well as small clubs, the rules are there," he told BBC Radio 5 Live. "A year ago, we warned that this is the last wake-up call for the clubs and that the rules have teeth.
"The break-even rule will enter into force next season, taking into account the figures of this season and last season.
"The clubs know the rules. If they haven't generated enough revenue to perform these transfers, then there will be sanctions - sanctions which could be a warning or a fine or a restriction on registering new players or, finally, an exclusion.
"The Financial Fair Play rules have been introduced and implemented not to punish clubs but to help the clubs.
Infantino also helps the restrictions will allow fans to have a voice in the operations of their club.
"It's important to keep the fans on board," he added. "Fans are the only ones who remain loyal throughout their life to the club.
"Everybody else sooner or later changes - players, managers, even owners - so a dialogue with fans to find the right balance is a good thing."