There are fears Dante Exum has suffered torn knee ligaments, an injury that would rule him out of Australia's Rio Olympic basketball qualifying series and potentially the entire NBA season.
The 20-year-old went down during the Boomers' 66-51 win over Slovenia in Ljubljana on Tuesday night, the team's fourth and final game of their European tour.
His left knee buckled as he drove towards the basket and, without contact, he collapsed to the floor.
The Utah Jazz youngster was treated onsite by Basketball Australia medical staff and will return to Salt Lake City for further assessment.
Boomers legend Andrew Gaze, along with a number of US media outlets, believe Exum tore his anterior cruciate ligament - which, after surgery, can take six to nine months to recover from.
It means Exum will miss the Boomers' two-leg Oceania championships against New Zealand starting on August 15 in Melbourne, which double as a chance to directly qualify for the 2016 Olympics.
It also puts in doubt his availability for the upcoming NBA season as the Jazz's starting point guard.
His injury has sparked speculation that Basketball Australia will recall fellow NBA point guard Patty Mills.
The San Antonio Spurs star was left out of the squad for the Oceania series because he was unavailable for the European tour, reportedly because he was continuing his recovery in the US from a shoulder injury.
While Gaze said such a move would go against BA's player-driven policy, he hopes they bring Mills back.
"Because ultimately it's about getting to Rio," he told SEN radio on Wednesday.
"I understand they had some rules and regulations put in place by the players, they'd come to an agreement to say 'in order to be eligible to participate in the Oceania Championships, you had to make yourself available for the European tour'.
"Because of injuries and recovery, Patty Mills wasn't.
"Now that we have these tragic set of circumstances where Dante Exum looks like he's done his ACL and will be out, it's an exceptional set of circumstances and with proper consultation with the team, and if they all support it, I would think that's appropriate."
The rest of the Boomers squad are due back in Australia later this week.
