Tom Johnson's Belgian outfit, who fought back from a 17-point deficit to stun Cajasol in Spain in the first encounter, did the double over Pedro Martinez's team and are now in select company.
Cholet and Virtus Bologna are the only other sides atop their respective groups with 5-0 records.
Cajasol went to the changing rooms at half-time on top at 33-30 but endured an almighty struggle when they returned to the court for the third quarter.
The visitors were held to just four points in the frame and went to the final quarter trailing 45-37.
They never recovered and ended up falling by seven.
Justin Cage had 16 points and Larry Owens 15 for Belgacom.
Juan Jose Triguero finished with a game-high 17 for Cajasol.
All is not lost for Cajasol.
If they win at home next week against BK Ventspils, they will advance to the Top 16.
For a team that is in last place in the ACB at 2-13, Cajasol and their fans will be taking nothing for granted.