The US territory was beaten 85-77 in the second leg of their final qualifying series against Chinese Taipei on Saturday, giving the visitors a three point aggregate win over two games in Mangilao.
Guam won the first quarter by six points to stretch their advantage to 11 points but lost the final three perios by a combined 14 points and missed a three pointer on the full-time buzzer that would have tied the series and forced overtime.
Head coach EJ Calvo admitted it was a tough way to lose.
"We thought we had a really good performance," he said.