Georgios Tsiaras and LaMarrGreer each scored 19 points as Olympia held off Zlatorog 83-82 to advance to the EuroCup Qualifying Round.
Theophanis Koumbouras added 14 points and nine rebounds as the Greeks moved onto the next round with a 155-146 aggregate victory over the Slovenians.
Nejc Strnad came off the bench to score 24 points for Zlatorog while Nemanja Jelesijevic added 21 points, 10 rebounds and three blocked shots, but it was not enough for the Slovenians, who lost by eight points at home last week.
Georgios Bartzokas's Olympia pulled ahead early on Corey Belser's three-pointer for a 14-7 lead.
Greer converted a three-point play and Tsiaras hit a foul shot to give the Greeks a 21-11 advantage after one period.
Ante Masic's lay-up trimmed the deficit to 23-17 early in the second only to see Mirza Kurtovik hit a long ball to help push the gap back to 29-18.
Strnad scored seven straight points for the Slovenians, who then pulled to within 32-30 on another foul shot by Strnad.
The Greeks did not relinquish the lead and Vasileios Giannoulakos made it 40-36 at the break.
After Zlatorog's Grega Mali started the second half with a three-pointer, Greer answered with a long ball of his own.
But Jelesijevic knocked down a three-ball and Strnad hit two straight from downtown as the Slovenians pulled ahead 48-43.
Lance Harris hit a three-pointer to keep Zlatorog even at 53-53 but Olympia led 56-53 going into the fourth.
Andrej Macek evened the game straight off with a three-ball but Greer's three-pointer helped the Greeks open a 62-56 advantage.
Jelesijevic hit a long ball and then three foul shots to cut the deficit to 66-65 And Strnad's two free throws gave Zlatorog the lead 69-68.
But the Greeks knew they had the eight-point advantage from last week and stayed close with the Slovenians.
Jelesijevic knocked down a three-pointer for an 80-77 lead with 39 seconds left. But Belser, Marios Batis and Tsiaras all hit two foul shots down the stretch for the victory.
Zlatorog coach Damian Novakovic:
"We played very bad just for a quarter in Lasko that’s the reason we’ ve lost. tonight we played much better with small players but in the final minutes we had some problems with personal fouls and our bench was not experience for that kind of the game."
Nejc Strnad, Zlatorog guard:
We had played better in the first game, one week ago and we played well in the second half, but we committed some turnovers and lost our rhythm."