Wisla Can-Pack Krakow held on for an 85-84 win at Gospic Croatia to finish 9-1 in EuroLeague Women Group B.
Ewelina Kobryn had another all-star performance for the Poles, scoring 15 points and corralling 14 rebounds.
In a remarkable story, Wisla have been one of the best teams of the EuroLeague.
Originally scheduled to be in the EuroCup Women, they left to join the EuroLeague Women just days before the start of the competition following the withdrawal of CSKA Moscow.
They nearly suffered a second defeat on Wednesday night but Jelena Ivezic and Ivana Jurcevic each missed jump shots for the Croatians.
Gospic led by five points in the third quarter but Wisla clawed their way back and went to the last frame on top, 63-61.
With 5:13 left, an Ivezic three-pointer knotted the contest at 71-71.
Janell Burse answered with two free-throws and a jumper.
After a three-point play by Andja Jelavic cut the Wisla lead to 75-74, Burse hit another jumper.
Jurcevic drilled a jump shot but Burse replied with another one of her own to make it 79-76.
The Poles then twice went in front by six points but Gospic refused to go away.
Carla Thomas drilled two three-pointers in the last 1:08 to make it 85-84 and after Katerina Zohnová missed for Wisla, the door was open for a Gospic win.
But the Croatian club missed its potential game-winning jump shots at the end to finish 1-9 in the competition.