Portugal surprised Slovakia on the opening day of Qualifying Round action at the U18 European Championship Division B Men in Debrecen, Hungary .
Joao Guerreiro had 19 points and 12 rebounds to lead the Portuguese to an 86-73 victory.
Slovakia, who won their group to start the new phase of the competition with a 1-0 mark, led 46-40 at half-time but Guerreiro and Co emerged from the locker room a different team and outscored them 23-13 in the third quarter to move in front.
They pressed home the advantage over the final 10 minutes to record a 13-point victory.
Matej Marchyn had 14 points to lead the Slovakians.
Poland thrashed Denmark 83-41 and lead Group F with four points ahead of Slovakia and Portugal (three points each) and the Danes (two).
In Group E, the Czech Republic showed their class once again to beat Sweden 94-76 while Slovenia had a much tougher fight with Austria before prevailing 80-74.
Mirza Sarajlija led the way for Slovenia with 18 points, four rebounds, four assists and two steals.
The Slovenians, who were 31 of 65 from the floor, including six of 14 from long range, led by just two points heading into the final quarter and did just enough to hold on.
Rasid Mahalbasic scored 12 points, hauled in seven rebounds and came up with two steals in defeat for Austria.
The Czechs and Slovenians each have four points to secure the semis from the group with Austria and Sweden on two points apiece.
In the Classification Round for ninth through 16th place, Group G saw Montenegro destroy Switzerland 73-57 and the Netherlands overpower Bosnia-Herzegovina 86-61.
In Group H, Romania prevailed 76-71 over Georgia and Finland beat Belarus 71-44.
The Classification Round for 17th to 20th place was also played.
England defeated Ireland 83-61 and Hungary shot down Norway 87-74.