Nevezis got off to a better start, taking a 12-4 lead following a bucket by Aurimas Adomaitis four minutes into the first quarter, but a 7-0 run by Ventspils quickly closed the gap.
Although the visitors from Latvia had shortly taken the upper hand in the second period, the hosts responded with a 15-3 stretch to jump into a double-digit advantage at 34-23.
Nevezis continued the strong play in the second half, extending the lead to a 21-point margin after a 9-0 spurt, with six points coming from Aurimas Adomaitis.
Having built a convincing 61-40 lead before the final period, the home side finished the game off with a solid fourth quarter, earning an important win against one of the main rivals in the group.
BBL leading scorer Arvydas Siksnius paced Nevezis with 16 points, also adding five assists, Aurimas Adomaitis added 14 points, while Valdas Dabkus finished the game with 11.
For Ventspils, point guard Lorenzo Williams was the only player in double digits with 12 points, Davis Lejasmeiers scored nine, as Toms Leimanis added seven.