Montenegro, Austria and Poland won close games on Friday - the opening day of the U18 European Championship Division B in Hungary.
The Montenegrins almost suffered a fourth-quarter collapse but beat Norway in Group A, 70-66.
Montenegro trailed 22-18 at the end of the first quarter but then outscored the Norwegians 23-8 for a 42-30 half-time lead and extended the advantage to 56-41 lead with 10 minutes remaining.
Norway refused to go away and closed the gap to 68-66 after Aksel Bolin's lay-up with 20 seconds remaining.
Milorad Sutulovic, who had a team-high 17 points for Montenegro, replied with a lay-up for the final score.
Austria beat the Netherlands 89-82 in the other Group A game. The Austrians were on top 71-60 with 7:56 left in the contest but the Dutch battled back and tied the game at 82-82 with a basket from Stefan Mladenovic.
Rasid Mahalbasic, the game's leading scorer with 28 points, made a lay-up for Austria who went on to score the last seven points of the game.
In Group C, England led 62-61 at the start of the fourth quarter but lost to Poland 88-81.
The Poles' 1.82m point guard Sebastian Szymanski stood out with 30 points, which included a four-of-eight effort from three-point range.
Romania defeated Belarus 69-62 in the other Group C clash.
In Group D, Slovakia thrashed Denmark 98-67 with Richard Grznár pouring in 24 points. The Slovakians broke open a close game with a 19-4 run over the last four minutes of the first quarter and stayed in command the rest of the way.
Hosts Hungary slipped up against Finland, 82-70. Matti Nuutinen finished with 22 points and 10 rebounds for the Finns.
Group B had Sweden overcoming Bosnia and Herzegovina 74-60 and Switzerland scraping a 72-68 victory over Ireland.