A super final quarter by Belgium in Coimbra was to prove the difference as the visitors left their Portuguese hosts disappointed after finishing with a flourish to take a 78-69 win to move to the summit of Group C.
It had looked like it would be the home team who might take the win since they held a slender lead heading into the last quarter after recovering from a terrible start to the contest.
Portugal had to call an early time out when they got off to a false start and were 12-2 behind during the early stages.
However after starting again and re-composing themselves, they pulled out a big second quarter to edge in front at 33-32 heading into the interval.
There was stalemate in the third period as both teams struggled to impose themselves on the game team and it was the home team with a narrow advantage when the last quarter began.
This was when Belgium made the game winning break as they posted a 16-4 run to move into a double digit lead at 65-55.
As hard as they tried, Portugal couldn't get themselves back into the game and Belgium kept their cool from the free-throw line to ensure they coasted home.
Belgium shot the ball really well both inside and out with Axel Hervelle epitomising the efficiency of the victorious visitors. He registered 15 points including a perfect 3 of 3 from outside while Beye Tabu-Eboma top scored with 23 points.
Heshimu Kenyatta Evans finished with 19 points and 7 rebounds for Portugal who are rock bottom of the table with three losses from three games.
Portugal Head Coach Moncho Lopez:
"We managed to overcome a bad start with the defense quality brought to the game by bench players. But, unfortunately, turnovers in the last quarter were decisive allowing Belgium a few easy baskets.
Belgium Head Coach Eddy Casteels:
"We have a lot of respect for the Portuguese team and we knew that it will be a hard game for us. It was tough but the team was focused and, on second half we managed to stop three point shooters and that was the key to win."