Croatia withstood a strong second half fightback to beat Montenegro 76-72 and continue their perfect record at EuroBasket in Cluj-Napoca.
They are now guaranteed to progress to the knockout rounds from Group C.
Croatia, who have not won a medal at the championships since a second successive bronze in 1995, led 43-31 at the halfway point against their Balkan rivals.
The gap was closed by two points in a 21-19 third quarter before a 20-14 finale ensured a close finish.
Bojan Bogdanovic was on fire early for the Croatians at the Polyvalent Hall, collecting 19 of his 23 points in the first half.
Spain remain group favourites, though, as they continued their unbeaten record by thrashing Romania 91-50.
Hungary also claimed a first win elsewhere in the group by beating Czech Republic 85-73.
In Group D, Russia also gained a third successive win by overpowering Belgium 76-67.
They are also now guaranteed to progress.
Aleksei Shved had another dominant display on the offensive end for Russia with 20 points, six rebounds and six assists to his name.
All matches in the group are taking place at the Ulker Sports Arena in Istanbul.
Latvia also gained their second victory after a 97-92 success over winless Great Britain.
Serbia also beat hosts Turkey 80-74.
Action is due to resume in the other two groups tomorrow with matches in Helsinki in Finland and Tel Aviv in Israel