Two-time defending champions Spartak Moscow Region won 79-70 at home against Ros Casares on Wednesday to claim the last remaining place on offer at the EuroLeague Women Final Four.
USA center Sylvia Fowles scored 23 points and pulled down 13 rebounds while compatriot Diana Taurasi contributed with 22.
Spartak won despite turning the ball over 24 times.
The Spanish team will be hugely disappointed with the setback as for the second year running their hopes of reaching the Final Four were crashed.
After losing a thrilling opener away at Spartak, Casares won in Valencia on Friday but failed to take the decider.
Delisha Milton Jones led Casares with 18 points but was three of 11 (27.2%) from the floor while Amaya Valdemoro finished with 14.
Spartak led 25-18 after 10 minutes played, with the Russian club´s Sue Bird leading all scorers with 12 points.
The home side stretched their lead to 32-21 with eight minutes to go in the quarter.
Ros battled back and Elena Tornikidou made two free-throws to cut the gap to 42-41.
Fowles finished the scoring with a jumper to give Spartak a 44-41 advantage at the break.
Ros Casares fought Spartak every inch of the way in the third quarter and even went in front at 54-53 when Milton Jones made a three-pointer.
The advantage grew to four when Spain point guard Elisa Aguilar buried another three midway through the third period.
Tornikidou should have increased her team´s run but missed both attempts from the charity stripe with less than three minutes to go in the quarter.
Taurasi then came up strong for Spartak, scoring nine consecutive points - two free throws, two three pointers, the latter a four-point play after a Tornikidou foul - to put her team 63-59 in front heading into the last 10 minutes.
Taurasi led all scores with 20 points going into the final frame.
Spartak then went cold at the beginning of the fourth quarter, failing to score for three minutes and three free-throws by Milton Jones cut the deficit 63-62.
Fowles stopped the rot splitting two at the line to start a 9-2 run for 72-64 lead with 3:32 seconds remaining.
Milton Jones went to the line and made both attempts to close the gap 73-69 with 1:42 to go.
The Spanish outfit got no closer.
Marina Karpunina made two from the line and Spartak pulled away for a nine-point win.
Spartak were superior shooting the ball.
The Russians finished 18 of 41 (43.9%) from two-point range and were eight of 17 (47%) from outside the arc.
Ros Casares were 19 of 47 (40.4%) from inside the arc and five of 18 (27.7%) from three-point range.
Spartak outrebounded Casares 37-29.