US Valenciennes stayed within striking distance for a half but were then blown away by undefeated Ros Casares on Tuesday on the opening night of the EuroLeague Women eighth finals.
The Spanish side led 40-30 early in the second half and then put the defensive clamps on their opponents from France and pulled away for a decisive 70-44 win.
Russia international Elena Baranova had a game-high 12 rebounds and came up with three steals to go with her 10 points for Ros, who won all 10 of their games in Group D.
Delisha Milton-Jones led Ros with 12 points while Evani Maltsi also scored 10.
With the Ros defense picking up its intensity, Laia Palau and Milton-Jones each had four points in an 8-0 run to open up a 48-30 lead at the start of the third quarter.
Former champions USVO never recovered.
Elena Tornikidou had six points as Ros claimed an early 15-6 advantage, but USVO clawed their way back and cut the deficit to 21-17 on a jumper by Réka Cserny, who would end up leading all scorers with 13.
Baranova replied with a three-pointer, though, extending the lead back to 24-17 and Ros were never under threat again.
Manolo Real, Ciudad Ros Casares coach:
"The key has been in the defense, which has been spectacular. When the individual effort works towards the collective service, things work better. The victory is important, but we still have one game to go".
Hervé Coudray, USVO Valenciennes:
"Today Ciudad Ros Casares has demonstrated they are a better team than us. It says something that the Spanish team came to the appointment with ten consecutive victories in the Euroleague Women. In Valenciennes I hope for a different game."