Scotland and Edinburgh number eight David Denton will face three months on the sidelines after he suffered a torn hamstring in pre-season.
The Zimbabwe-born back-rower endured a difficult campaign last season, missing the June Tests in the Americas and South Africa because of concussions he suffered in club action.
Having recovered from that, he was back in action playing touch rugby ahead of the start of the new season, but he now faces a race against time to be fit for Scotland's November Tests, with Edinburgh coach Alan Solomons planning for a return in November or December.
"Dents will be out for a while," Solomons told The Scotsman. "He definitely will not start the season and I think we will be looking at November or December for him to be back playing.
"He did nothing for seven weeks over the summer because of the concussions he had and we were very cautious bringing him up to speed with training.
"It is just one of those things you know, the guys were playing a conditioning game and unfortunately he was injured."