Looking to keep pace with Group C leaders UMMC Ekaterinburg, Ros claimed a 91-61 victory although they didn't take command until the second quarter.
Leading 27-25 with 5:39 to go in the first half, Amaya Valdemoro made two free throws to trigger a 9-0 run that was capped by a Roneeka Hodges three-pointer.
Just three seconds into the second half, Hodges drilled another three-pointer and Ros pulled away for a decisive victory.
Valdemoro scored 19 points and Delish Milton-Jones 17 for Ros.
Hodges finished with 13 points for the Spanish giants who nailed nine of 20 shots from behind the arc.
Laia Palau, Ros Casares Valencia player :
"We knew that we had to win every game to have the best place possible in our group. We are happy to do so tonight. Our victory against UMMC gave us courage, we are in a good period now."
Fabrice Courcier, Hainaut Basket coach :
"During the first half-time, we played as a collective so we played at the same level as Valencia. Then, in the third quarter, Valencia played more aggressive and had a good percentage on three-pointers. Valencia was really the better team."