The Ospreys have rejected the possibility of young fly-half Matthew Morgan joining Cardiff Blues on-loan this season.
The Blues are now searching for fly-half cover with Rhys Patchell ruled out for the next four months due to knee and shoulder injuries.
With Dan Biggar set to be away with Wales during the Six Nations, the Ospreys would only have Sam Davies left if Morgan moved to the capital.
The Blues on the other hand only have Gareth Davies left at fly-half, with Leigh Halfpenny training at number ten in case he is needed for this weekend's Heineken Cup clash against Toulon.
""That won't be happening. He's our player and he's great in this period for us," Ospreys head coach Steve Tandy told the South Wales Evening Post.
"We don't have a squad as large as some of the giants around Europe, so we won't be open to leaving our players go.
Dan will be away for a long time, and we see Matthew playing a major part for us over the Six Nations period and helping us go through and make the top four in the Rabo.
You need three players in each position. Biggs could tweak a hamstring tomorrow and Matthew could potentially be featuring against Northampton on Sunday.
"We are in a great position in the Pro12, but you need big squads."