Russia used a 16-1 spurt right after the break to open a double-digit lead and see off defending champions Serbia 74-55 in the U18 European Championship for Women.
The Russians trailed 31-29 at the break, but came out all guns blazing to outscore their opponents 25-12 in the pivotal third quarter.
The team's head of delegation, Sergey Fedorenkov, credited a much-improved lock-down defense for the team's easy baskets at the other end as last year's bronze medallists improved to 3-1 in Group F.
"We didn't play good perimeter defense against Sweden on Tuesday and they made us pay with their three-pointers," he said.
"So we worked on that and it seemed to be there for us tonight."
The Russian defense was so good that they held their opponents without a field goal for the first 6:28 of the second half.
Serbia's open looks and easy lay-ups were few and far between in the last two quarters and they blew some of the easier ones.
The defending champions recovered some of their shooting touch early in the final frame to come within seven, 54-47, but Russia once again went back to basics, increasing their defensive intensity which, in turn sparked their fast-break game.
Anna Ostroukhova led Russia with 18 points and Anastasia Logunova had a strong double-double of 17 points and 13 rebounds.
Serbia had used their height and power inside to take a 17-9 lead by the end of the first quarter, with Tina Jovanovic converting two three-point plays as Serbia asserted their authority down low.
Russia used an 8-0 run over the first 1:40 of the second period to cut the deficit to one, 17-16 on Olga Bodganova's three-pointer and kept the momentum on their side to take a 22-19 lead on Anastasia Logunova's lay up.
Serbia's offense stalled for a while to the extent that their inside players were trying to beat their counterparts on the perimeter, but they eventually restored order and scored six unanswered points to edge back in front, 25-22.
Russia tied the game at 29 all on Anna Ostroukhova's three-pointer before Jovana Popovic's lay up gave the defending champions a 31-29 half-time lead.
Serbia, who were led by Popovic's 18 points, dropped to 1-3.