Wednesday night's 69-64 win improved Prague's record to 4-6, but they have an inferior goal differential against Lotos PKO BP who are also 4-6 and that means a fourth-place finish and Eighth-Finals clash for the Czechs against Spartak Moscow Region.
Because of Lotos PKO BP's 14-point triumph in the first leg, Prague needed to win big to avoid Spartak, and in the third quarter that looked possible.
The game was knotted at 33-33 at half-time, but Lubor Blazek's Czechs held Lotos to just six points in the first seven minutes of the third quarter and opened up a 56-39 advantage.
Lotos PKO BP finished the quarter on an 8-1 run to trail 57-47 and nearly came all the way back in the fourth.
Emilija Podrug's two free throws cut the Polish team's deficit to 63-62 with 3:14 remaining.
Sonja Kireta, who had 18 points and seven rebounds for Prague, replied with a jumper and Lotos PKO BP got no closer than three points the rest of the way.
Alana Beard poured in 20 points for Lotos PKO BP.
"It was a match for third place, it wasn't just about winning, but also about gaining a good position for the play-offs. I'm glad we won, but I had hoped we could win at least by 14 points. We didn't manage that. At the point where we were leading by 17 points and it seemed we could succeed, we made mistakes in our zone defense. We had problem with our physical condition too. In the last two weeks we had many players ill or injured, we started preparing on Monday and that also affected the result. However it's not good to have our last match [in the group] being a decisive match, we should had played with more concentration in Gdynia and not lose in Croatia and France."
Jacek Winnicki, coach Lotos BP PKO Gdynia:
"We accomplished what our goal was, it is a good result. It was a good match except the end of first half and the start of the second one. Being down by 17 points was a disaster, but it's important we regained control. We were able to play smart against zone defense. Congratulations to USK."