Vieru collected 16 points and 10 rebounds while Yulia Lukina also scored 16 points and both Katerina Keyru and Olga Zhuzhgova added 11 points off the bench.
Snezana Aleksic paced Montenegro with 21 points while Milica Jovanovic added 19. No other player scored more than seven points for Rade Petrovic's team, which was promoted to Division A after winning the Division B title last summer.
Alexander Kovalev's Russia side jumped ahead 21-9 in the first quarter as Irina Romanova and Vieru combined for 17 points. The advantage grew to 21 points at 36-15 midway through the second quarter, which ended with Russia up 51-24.
The Russians did not let up in the third period, increasing the lead to 36 points before finishing the third ahead 75-41.
Montenegro used one final spurt to move within 77-51 with six minutes left. But they could not get any closer the rest of the game - even against Russia's reserves.