Pending the outcome of an ongoing appeal from West Ham, it means the Spaniard could potentially miss the next three games against Bournemouth, Liverpool and Newcastle.
And that potentially means a Premier League debut for summer signing Darren Randolph who was brought in on a free transfer from Birmingham City before Bilic even took over this summer on the advice of West Ham's legendary former goalkeeper Phil Parkes.
Fans were already fearing the worst based on what they have seen of the Irishman so far.
A string of mistakes and nervy displays in pre-season friendlies and the club's ill-fated Europa League qualifying campaign has left supporters with little or no confidence in the ex-Charlton man who could now be thrown into the deep end of the Premier League.
A statistic to make West Ham fans' blood run cold
But what Hammers fans may not know - and may not want to know - is that he will be facing the Cherries who put an astonishing 16 goals past him in three games last season.
That included eight in one game and four in each of the others.
Obviously those goals were not all down to Randolph and it would be cruel to suggest otherwise.
But regardless of his performance in those matches, there are bound to be mental scars from facing Eddie Howe's side, who will be licking their lips in anticipation.
It has been a shaky start for Randolph
Last season with the dependable and vastly experienced Jussi Jaaskelinen as back-up it would not have been cause for concern for West Ham.
But he has since been released and departed for Wigan Athletic with Randolph brought in as his replacement. The problem is, he has been decidedly shaky so far.
In West Ham's crucial Europa League away match against FC Astra in Romania he allowed a free-kick from 40 yards to sail over his head as he got caught underneath it and it struck the bar.
It got doubly lucky when the rebound almost cannoned off him and into his own net. That was just on example with poor kicking another major cause for concern.
All points to a lack of confidence from Bilic
It perhaps says everything about Bilic's confidence in Randolph, or apparent lack of it, that West Ham are so desperately appealing Adrian's red. Another sign is that Bilic is reportedly keen to re-sign former 'keeper Rob Green from Queens Park Rangers, as has been rumoured in the likes of the Evening Standard.
Imposing 6ft 5in Swiss youngster Raphael Spiegel played his first game for the senior side against Werder Bremen in pre-season and was very impressive, producing a world class save to add further pressure on Randolph.
The 'keeper is under the spotlight now and of course will be out to prove the doubters wrong and Hammers fans will be hoping he does just that with a confident display at Upton Park come the weekend.