England suffered their second loss to Portugal in as many days when going down 88-70 in Belem, giving the home side an unassailable lead in their three-match series.
England effectively dug themselves into a hole from the start, allowing Portugal to hit six three-pointers as the hosts raced to a 35-14 lead.
Paulo Simao, who led Portugal's scorers with 18 points, connected four times in the opening 13 minutes as his side raced out of the blocks.
Although captain Ronnie Baker, playing in his 142nd international, led a spirited recovery with 12 points in the second quarter, England still trailed 48-33 at half-time.
The only time England threatened to challenge was in the third quarter, when center Robert Reed hit an unlikely three-pointer to ignite a 9-0 run which brought the score back to just 54-49.
But Portugal answered with a full court press and restored the advantage to 63-51 at the end of the period and the lead never fell into single-figures thereafter.
In the fourth quarter, England's leading scorer Julius Joseph found himself at center stage.
He hit a three-pointer to reduce the deficit to 65-54, but was almost immediately called for a highly dubious offensive foul - his fourth foul of the day.
While England fumed about the decision, Portugal hit nine unanswered points and effectively ended the game as a contest.
Joseph, who had come in for some rough treatment at the hands of the Portuguese defence, left the game with a large ice pack on his knee after fouling out early with 23 points.
Reed gave his best display in an England shirt, adding 14 rebounds to his 16 points and Baker also scored 16, his highest total for his country since a game in Lisbon five years ago.
The final game of the series comes on Wednesday in Casal Vistoso, when coach Peter Scantlebury's team will seek some reward for their hard work in the opening two games and the training camp that preceded it.