The Boomers have lost 93-83 to Canada in a high-quality Olympic basketball battle that leaves Australia needing to fell Giannis Antetokounmpo's Greece to ensure a quarter-final berth.

Australia played wonderfully in Lille on Tuesday to lead by four points at half-time, before Shai Gilgeous-Alexander, RJ Barrett (24 points, seven rebounds, five assists) and their NBA support cast overwhelmed them to seize control of their Olympics pool of death.

Gilgeous-Alexander was practically unstoppable for the World Cup bronze medallists, scoring 16 points in just 25 minutes on eight-of-10 shooting.

Josh Giddey had won the earlier exchanges (19 points, seven rebounds, six assists) before his former Oklahoma City teammate took control in the second half.

Tokyo bronze medallists Australia, who impressively beat Spain in their Games opener, will play the winless Greece on Friday.

Victory would likely see them finish second and earn a ticket to Paris's quarter-finals, while a loss would likely leave them among a pack of teams hoping to be there as one of the two best-performed, third-placed teams.

Things began brilliantly as Australia shared the love in Lille on Tuesday, highly-efficient offence and swarming defence offsetting the brilliance of emerging NBA superstar Gilgeous-Alexander in the first half.

Patty Mills and Jack McVeigh hit crucial triples, Jock Landale (16 points, 12 rebounds) was clever around the rim, Dante Exum (15 points) impactful in his return from injury and Dyson Daniels was again a problem on defence as they led by five.

But Canada put the heat on Giddey and the Boomers began to leak turnovers, with more tough shots from Gilgeous-Alexander, Barrett and Lu Dort putting them up 10.

Exum's return changed the mood though, the Dallas guard driving to the rim and sparking a comeback that, after two late McVeigh triples, had Australia down by two at the final break.

They couldn't buy a bucket in a 21-13 fourth quarter, Gilgeous-Alexander icing the cake with a neat alley-oop pass to Dwight Powell for an 11-point lead with one minute to play.

Earlier, Spain kept their Games hopes alive with a 84-77 defeat of Greece, Santi Aldama the hero with 19 points and 12 rebounds.

Antetokounmpo had 27 points and 11 rebounds for Greece.