Belgacom Liege claimed a remarkable 79-78 comeback win at Cajasol to finish off an excellent night for the Belgian teams in the EuroChallenge.
Tom Johnson's team trailed by 17 points in the first half but clawed its way back in the third quarter and went to the fourth behind 66-65.
They took the lead for good at 77-74 when Larry Owens made a three-pointer with just over four minutes remaining in the game.
Despite the visitors going on top 79-74 with 3:25 left in the contest, Cajasol had good opportunities to go back in front.
With Liege leading 79-78, Cajasol turned the ball over but got it back and had two chances to go ahead in the final 23 seconds.
Each time, Pedro Rivero del Caz was off target with jump shots - the first with a three-pointer.
"This is a very important win for us and for our club," Johnson said.
"The ACB is the best league in the world next to the NBA, and Cajasol has a team with more potential than the Belgium teams.
"Our players were very motivated today. It was very beautiful to see how we came back from 17 points down and won the game."
Cajasol were left stunned by the result.
Juanjo Triguero, one of the Cajasol players, said: "It's incredible the way that we lost the game.
"We played well in the first half, but in the second we had more problems on defense, especially with their shooters from the three-point line."
Belgacom ended up hitting 13 of 24 shots from long range, with Christopher Hill burying seven of 10.
The visitors also got a wonderful game from Will Thomas, who had 17 rebounds to go with his 11 points.
Pedro Martínez, who was recently installed as the Cajasol coach following the remove of Manel Comas, said: "The game had two different parts.
"Early on we played very well and we defended well.
"In the second part, we did not defend well and they have made three-pointers easily.
"We were not focused when they were pulling ahead, so we have collapsed when they tied the game. We have lacked balance and calm."
Triguero finished with 15 points and nine rebounds for Cajasol, who are bottom of the ACB standings with just one win.
They lost in overtime on Sunday to Kalise Gran Canaria.
Belgian sides Dexia Mons Hainaut and Base Oostende also won their games on Tuesday.