It's feared the 20 year old tore knee ligaments in Australia's 66 51 win over Slovenia in Ljubljana early Wednesday morning, their fourth and final tour match in Europe.
The early but unconfirmed prognosis is a torn anterior cruciate ligament which, after surgery, can take anywhere from six to 12 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.
Jazz teammate and fellow Boomer Joe Ingles spoke to Exum soon after he suffered the injury from Sydney.
"He was obviously pretty down," said Ingles, who is sitting out the Boomers' qualifying campaign to recover from a tough first NBA season.
"It didn't look great but obviously you hope for the best and hope it's not (a torn ACL).
"Me and Dante are really good mates, roommates, and obviously playing in Utah this year, it was another step of our friendship.
"I'm just really disappointed for him all the work he did at the end of last season, especially the second half of the year and what he did for our team, he proved that he's an NBA player.
"But we'll get behind him and support him when we find out the official news."
His injury opens the door for fellow NBA point guard Patty Mills to return to the national side.
The San Antonio star was controversially ruled out of the Oceania series after he and the Spurs decided to miss the Boomers' European tour to continue rehabilitation on his surgically repaired shoulder.
Even if Mills isn't on the official squad list submitted to the governing body FIBA, BA can add his name up to seven days before the opening game if they pay a Authentic nfl jerseys $7000 fine.
Boomers legend Andrew Gaze said that while such a move would go against BA's player driven policy, he hopes Mills is brought back.
"Because ultimately it's about getting to NFL jerseys wholesale Rio," he told Melbourne's 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.".