Mitchell Starc has become the first player to take the provocative step of aligning with a rival to one of Cricket Australia's protected sponsors as the sport's industrial war rages on, a Sydney Morning Herald report says.

The Australian Cricketers’ Association (ACA) has been trying to rile in sponsors who had been approved by Cricket Asutralia (CA) but it has also sought rival sponsors.

Mitchell Starc has signed a sponsorship deal with Audi that may lead to further uneasiness for Cricket Australia – which has included fellow car company Toyota among its so-called 'protected sponsors' for the 2017-18 season. 

Pat Howard, who is the CA team performance boss had earlier cautioned the players against signing ‘unapproved endorsements’ as such moves will jeopardize a future contract with CA.

Toyota had taken up an option for a new deal with CA after their previous contract ended on June 30.

Starc could argue that his sponsorship with Audi is a pre-existing one since it was signed last week.

Starc’s move serves as a message to the governing body that players are serious about a fight to retain a share of revenue.

Earlier, captain Steve Smith said via an instagram post: "I'll say what we as players have been saying for some time now: we are not giving up the revenue-sharing model for all players."