Scotland inside centre Alex Dunbar will travel to the USA to continue the recovery of his injured knee with a world-leading rehabilitation specialist.
Dunbar was set to start against England in the Six Nations in March but ruptured his knee ligament (ACL) in training a few hours before the squad's departure.
After swift surgery in an attempt to get him back in time for the World Cup, the next phase of recovery for the Glasgow Warrior is a visit to Philadelphia.
Dunbar will spend three weeks there before re-joining the national squad.
"We're pleased to say that Alex remains on schedule at this stage and that, 14-weeks down the line, he is now in the right place for this trip to the States," Scottish Rugby Head of Performance Medical, Paul McGinley, told thescotlandteam.com.
"Evidence suggests that the earliest you could expect somebody to safely recover from ACL reconstruction is around six months, and that is tight; but that's the timescale to which we're working if he is to feature in the Rugby World Cup.
"That's been the focus from the start. We're doing everything we can to give him the best chance of keeping to that timeline and making the competition, while paying close attention to the his long-term welfare."
Since surgery, Dunbar's focus has been to build strength and stability in his knee, before progressing into running on an anti-gravity treadmill that allows him to run with less force and impact.
McGinley added: "There's another, crucial, rehabilitation phase coming up, with the view to getting him game-time before the world cup, providing we can stick to the recovery schedule."