Scotland full-back Stuart Hogg is likely to sit out all three of the Dark Blues' Autumn Tests after he was forced to undergo surgery on an injured wrist.
Scott Johnson's side play Japan, South Africa and Australia next month but the interim head coach says he will "probably" have to do without the British and Irish Lion.
Hogg, 21, suffered the injury playing for club side Glasgow against Leinster three weeks ago but with recovery time from the operation needed, it appears he will not be back in action until December at the earliest.
Johnson told Press Association Sport: "Are we counting Hoggy out of the Autumn Tests? Yeah, probably. There is a chance that he might make a game but that is unlikely.
"However, this is just a chance to blood someone else."
While Hogg is out of his short-term plans, Johnson is refusing to give up on Perpignan fly-half Tommy Allan.
The 20-year-old nephew of former Scotland international John Allan has been called up by Italy for a training camp later this month, with the Azzurri considering capping him in one of their November Test encounters with Australia, Fiji and Argentina.
But Johnson is still hopeful that Allan will chose to represent the land of his Scottish father William rather than that of his Italian mother Paola Berlato.
"Tommy was always on our radar," he said. "We haven't said anything else. We have been in dialogue with him but - and I will keep saying this - I will only pick players who want to play for Scotland.
"It's not about a change of heart. The conversation we had will remain between myself and the lad. He's a young man caught in the middle of something.
"He's got to sort his mind out and we will give him time to do that."
If Allan does decide to pledge his allegiance to Scotland, he will not be the only new face in Johnston's group when he names his squad for the Autumn Tests later this month.
Ten players were handed their first caps during the summer tour of South Africa as the interim head coach sought to "broaden" Scotland's pool of players with international experience.
And Johnson plans to do the same again next month before he hands over the reins to incoming boss Vern Cotter next year.
He said: "We spoke in the summer about giving new players a chance because we wanted to broaden our base. I'm going to do it again. I have to.
"I've got a plan in place. We have Vern coming in in the middle of next year. I want to make sure we have broadened it all by then so we have a clear view.
"We showed we got more talent expected on the summer tour. Some guys stood up and showed they are ready to go. There are a couple more out there as well. With the World Cup coming up, we need to find out if it is a year too far for some, or if the mileage on the clock is right. It's a juggling act but it's my job to do it.
"I don't speak to Vern every day, we're too busy. But he is fully aware of what is going on and I'm flying out to see him in a couple of weeks when we will have a catch up and see how everything is."