Sunderland boss Steve Bruce has predicted it will be only a matter of time before a player challenges the transfer window system as a restriction of trade.
The Black Cats faced an anxious wait to see if they had landed Manchester City striker Benjani Mwaruwari on loan earlier this week after communications problems left the Football Association and the Barclays Premier League to make a decision on whether or not the deal had gone through in a mad rush before Monday's 5pm deadline.
Bruce believes the 31-year-old Zimbabwe international could have been a case in point had he not managed to secure a temporary move to the Stadium of Light.
He said: "I wouldn't be surprised if a player stops it by saying it's a restriction of trade.
"Take Benjani for example: Benjani has come up here now to try to earn himself a contract. If the deal hadn't gone through, then it restricts his career, it restricts his movement.
"That's why we carry the squads we carry. They are too big and we can't keep them all happy."