FIFA's punishment of Chelsea through a transfer ban over their signing of Racing Lens teenager Gael Kakuta is a warning shot to the game's biggest clubs, leading sports lawyers said.
Chelsea said they would mount the "strongest possible appeal" after soccer's world governing body banned the Premier League club from registering new signings until 2011.
FIFA found Chelsea guilty of inducing Kakuta, now 18, to break his contract with the French club in 2007.
"The FIFA regulatory regime is there to ensure contractual stability so clubs can plan their seasons (and) their squads...
"This is an example of FIFA showing just how important it views the regulations," said Dan Lowen of sports business law firm Couchman Harrington Associates.
"The ramifications at the club are potentially huge, not being able to sign anyone until 2011 which could have huge implications for a club of Chelsea's size and stature," he told the BBC.
The west London club were fined in 2005 by the Premier League for tapping up Arsenal fullback Ashley Cole and that case may have been a factor in FIFA's punishment, Adam Morallee of London law firm Mishcon de Reya told Reuters.
"With Ashley Cole it was 300,000 pounds ($489,500) but... it didn't matter," Morallee said, referring to what is a relatively small sum for a club backed by billionaire Roman Abramovich.
"This does matter. It's a case of a governing body laying down a punishment that actually affects a big club. They (Chelsea) only care about points deductions and not being able to do deals.
"Maybe this is a move by governing bodies to say that if you break the rules you will get slammed by a massive punishment.
"In terms of the impact on the game it seems a little harsh but when one looks at the wider issue of how people treat minors, FIFA and UEFA will say that this about the game and how we treat young players going forward."
Morallee said Chelsea would be on dangerous ground if they attempted to gain an injunction against the ban at the High Court citing a restraint of trade, rather than take their appeal to the Swiss-based Court of Arbitration for Sport (CAS).
"Chelsea are obliged to go through CAS under FIFA rules but they might think to try and get an English judge because English judges hate restraint of trade," added Morallee.
"But if Chelsea do take that route they will make themselves a pariah in football. It would be very high risk."
He said Chelsea's most likely route would be to appeal to CAS, as Swiss club FC Sion did this year in a similar case, which would allow them to continue trading in the next transfer window while the appeal was heard.
"CAS effectively suspended the operation of the (Sion) ban until a decision was reached so by doing that they got round it. That would be one tactic open to Chelsea."