Charles Green has accused players who have refused to transfer to his newco Rangers of "opportunism".
Steven Davis, Allan McGregor, Kyle Lafferty, Jamie Ness, Steven Naismith, Steven Whittaker, Sone Aluko and Rhys McCabe have so far all confirmed objections to transferring their contracts to Green's Sevco company.
The squad are due to report back to Murray Park for the start of pre-season training on Thursday but only Lee McCulloch and Lee Wallace have indicated they plan to commit to Green's new regime, and he told Sky Sports News: "I'm very, very disappointed of course."
When quizzed further about the eight who have refused to transfer their contracts under TUPE employment regulations, he added: "It is clear in the regulations, if someone has an objection they have to notify within 24 hours, this is nearly two weeks.
"I think this is just opportunism. We will definitely challenge it, yes."
Asked whether he expects more players to try to quit the Ibrox side, Green added: "I've learnt not to expect the expected at Rangers."
Green's application to join the Scottish Premier League looks doomed and he could be forced to relaunch the club in the Irn-Bru Third Division. A formal vote will take place on July 4 but six SPL clubs have already gone public with plans to reject the Rangers bid, with an 8-4 majority required.
Midfielder Davis, who joined Rangers in 2008 and captained the club through four months of administration, claimed he had to put his career first after turning down a move to the newco Rangers.
In a statement published in the Daily Record, Davis said: "I signed a new contract last year, giving my best years to the club in the knowledge we'd be challenging for leagues and cups and in Europe year after year. That's the reason I came to Rangers.
"My young family love life in Scotland but after all that's gone on since administration in February, there came a point when I needed to make a decision based on what was best for my short career. I am 27 and need to be playing at the highest possible level."