Rockets' Landale out of Australia's basketball World Cup campaign
The Boomers' starting centre hurt himself during a warm-up match with South Sudan in Melbourne on Thursday and scans showed "a lateral ankle ligament injury".
Coach Brian Goorjian said it was a huge disappointment.
"The team is really hurting for Jock. He's a big part of the culture in this team and everybody loves him," Goorjian said.
"He was really excited about this, so it's a real kick in the guts, but as far as our belief -- that hasn't waned."
Landale will head back to Houston to prepare for the NBA season.
"All the build-up and preparation we go through as athletes just to have it yanked away 12 hours beforehand sucks," he tweeted as the Australian team departed for Japan.
"Focus turns to supporting them how I can and preparing for this season with the @HoustonRockets."
The Boomers were already without Brooklyn Nets guard Ben Simmons who opted out of the World Cup, which runs from August 25 to September 10 in Japan, Indonesia and the Philippines.
But they have a slew of other NBA players on board, including veteran Patty Mills and rising star Josh Giddey.
Australia finished fourth at the World Cup in China in 2019 and third at the pandemic-delayed Tokyo Olympics in 2021.