Australian welterweight boxer Cameron Hammond was beaten 14-11 by Canadian Custio Clayton in their last 16 clash on Day Seven.
The 69kg boxers were tied on points entering the last round, but the Canadian pulled away as Hammond allowed his smaller opponent to fight at close range.
Clayton landed numerous left hooks which, as the round wore on, he combined with right uppercuts and crosses.
One uppercut rocked Hammond with 30 seconds remaining and the Moree fighter did well to stay on his feet as the Canadian continued to swing accurately.
The first round was an even affair which the judges ruled two apiece.
Hammond seemed a little fortunate to still be even - at 5-5 - after the second stanza in which he threw little leather, but even at this stage the fight appeared to be ebbing away from him.
The Australian said he was surprised to find energy sapped going into the final round, leaving him unable to quell his marauding opponent's attacks.
"I was feeling good after two rounds. If I could have kept the pace I had in the first and second rounds I would have won it," Hammond said.
"I just lost energy. I don't know what happened. I just went flat.
"I definitely thought I would do way better than this.
"I wanted to slug it out to show I could do it too, but it didn't go my way."
This defeat leaves Australia with two male boxers left from their original squad of 10 men - Damien Hooper and Jeff Horn, both of whom fight on Day Eight.