Wing Shane Williams is one of the Ospreys required in Wales camp
Ospreys have failed to move Sunday's Magners League fixture against Glasgow to Saturday, BBC Wales understands.
As a result they will be without at least five of their star players, who are joining up with the rest of the Wales squad ahead of the autumn Tests.
Wales coach Warren Gatland can call on players 13 days before his side face Australia on Saturday 6 November.
Alun Wyn Jones, Andrew Bishop, Jonathan Thomas, Shane Williams and Lee Byrne will definitely miss the Ospreys' game.
An Ospreys source told BBC Wales that elite performance director Andrew Hore, broadcaster S4C and Gatland approached the Magners League two weeks ago to ask for the Glasgow match to be switched, but the request was turned down.
The Welsh region is understood to be disappointed with what it sees as the lack of flexibility shown by the league.
There are 10 other Ospreys players who this week were named in Gatland's squad for the autumn international series, which sees Wales face the Wallabies, South Africa, Fiji and New Zealand on successive weekends.
Gatland has spoken publically about his desire to see Ryan Jones in action for Ospreys against Glasgow on Sunday, while Mike Phillips and James Hook are also in need of game time after having also missed much of the start of the season - like Jones suffering from lengthy injuries.
Front rows Paul James, Adam Jones, Huw Bennett and Richard Hibbard, lock Ian Gough, plus fly-half Dan Biggar and wing Tom Prydie are the other Ospreys in the Wales squad.
At this point the expectation is that only the five players named will be unavailable to face Glasgow, although this could change once the situation becomes clearer.
The Magners League has been asked by BBC Wales to give its view on the situation but has yet to respond.
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