Two of Keighley Cougars rivals, Batley Bulldogs and Doncaster, have both been docked three points by the Rugby Football League for fielding ineligible Super League players in recent Kingstone Press Championship matches.
The clubs appeared in front of an RFL operational rules tribunal after being charged with breaking dual-registration regulations and were found guilty of the offence.
The punishment is particularly significant for John Kear's Batley, who drop into the relegation zone as a result of the deduction. Five clubs will be relegated to Championship One this year to make way for a new-look league structure in 2015.
Doncaster remain in fourth place despite the points deduction, although they have lost ground in their pursuit of a top-three finish. They have already announced their intention to appeal.
The big beneficiaries of Friday's announcement are Whitehaven, who climb out of the bottom five as a result.
The charges arose from Batley's decision to play Huddersfield second rower Jacob Fairbank in their win over reigning champions Sheffield Eagles and Doncaster's fielding of Hull centre Ben Crooks in their victory over Keighley.
Both matches were played on Sunday, July 27, two days after the registration deadline for the Championship closed.
An RFL statement said: "Batley and Doncaster were found guilty of breaching operational rule B3.17 which states that dual-registration players who have a salary cap value of £20,000 or more must have played in at least three league fixtures for the Championship club that season before the end-of-season registration deadline in order to play in games which fall after the deadline, whether they be regular season or play-off games."
Batley, who face a crucial derby fixture with Dewsbury on Sunday, have yet to announce whether they will accept the ruling but Doncaster chief executive Carl Hall says his club will fight it.
"Whilst we do not dispute Ben played in the game, based on communications and dialogue we have had with the RFL prior to the player participating in the game, we are disappointed with the outcome of the hearing and the punishment that has been provided," Hall said.
"We can confirm we will be appealing the decision."
Cougars chairman Gary Fawcett urged the RFL to apply the rules properly when the offences came to light last week.