The win allowed the Lithuanians to climb atop Group B, with a 3-0 record, while Ventspils dropped to third place, having won two matches and lost one.
After the first quarter, the visitors from the Latvian seaside had a slight 24-21 edge, which they increased to 32-23 at the start of the second period.
However, an and-one play by Siauliai’s captain Darius Pakamanis just seconds before halftime tied the game at 41-41 after two quarters.
Although Ventspils opened the scoring in the second half, Siauliai responded with a 14-3 run, which put them up by double digits at 56-46.
Having started the final ten minutes of play with a 64-53 advantage, the home team didn’t allow last year’s strongest team to make a run, keeping them at arm’s length until the final buzzer.
Darius Pakamanis and Vytautas Sulskis scored 17 points each for the winners, with Pakamanis also adding eight assists, while Christopher Cooper chipped in with a double-double of 16 points and 13 rebounds.
The only player in double digits for Ventspils was Ronalds Zakis, who finished the game with 17 points, as Sandis Valters scored nine.