Earlier on Thursday afternoon, the QPR forward posted a cryptic tweet that West Ham fans believed was aimed at Sullivan. On this occasion, though, there was no doubt and no need for speculation.
Indeed, pulling no punches, Austin labeled Sullivan's claims to be an 'outrageous slur' and made his 'injury problems' fully clear for all to see.
In a KUMB podcast, West Ham co-owner Sulllivan had suggested the 26-year-old is not fit enough to take a risk on, with many members of the Hammers faithful this summer urging the club to sign the QPR man as an answer to their current striker problems.
And, following Austin's firm response, it appears any chance of a move could be off. Things could U-turn from here - as Fabian Delph proved a few weeks back, anything is possible in the transfer market - but the QPR forward has clearly taken offence to the West Ham man's comments. Is there no coming back from here?
His statement, meanwhile, prompted a variety of response from Irons fans...
@chazaustin9 obviously not gonna be West Ham now. So good luck to you wherever you end up— tony hall (@tonyhall84) August 20, 2015
@chazaustin9 dont take it personal mate he just fobbing off us Hammers— Gal -WHUFC (@1972whufc) August 20, 2015
@chazaustin9 can u blame him I think u a really gd player Austin owner out of order saying that— Dale Smith (@TheHammerSmithy) August 20, 2015
COYI父 (@sportmurphy) August 20, 2015