Biggar has started all six of Ospreys' GUINNESS PRO12 games this season, contributing 70 points to help his side sit unbeaten at the top of the table.
However the club will be without his services for the next month having been called up to Warren Gatland's Wales squad for the Autumn internationals.
Former world junior player of the year Davies is set to be the man to step up in his absence, starting against Connacht at home on Friday.
The 21-year-old has made his four GUINNESS PRO12 appearances off the bench so far this season, but Tandy is confident the Welshman will flourish from the off.
"Sam is a special talent who will do a great job for us," he told the South Wales Evening Post.
"You only have to listen to him in some of our meetings - he understands how we want to play, he understands his own game.
"He doesn't lack in confidence, so it won't be bothering him who he is playing against or who he's up against this Friday.
"Sam has an outstanding future, but he has a lot of things he needs to work on.
"Ultimately, he'll do a real good job for us. If he gets to wear our shirt consistently I'm sure he'll be close to international honours."
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