Lithuania held off an inspired Russian side 76-69 at the U18 European Championship Men 2009 in Hagondange, France.
The win saw Lithuania remain unbeaten as they topped Group D while Russia finished third and are assured of a place in the Qualifying Round.
Lithuania looked as though they were headed for an easy win after making a strong push late in the second quarter to open a 49-38 lead at the half.
And they maintained control of the game after the break, answering every one of Russia's big baskets with one of their own and head into the final frame still in fine fettle, up 63-54.
Mikhail Solovyev's men scored five unanswered points to come within four, 63-59, but that would be as close as they would get as Jonas Valanciunas came up big for the Lithuanians, scoring seven of his team-high 20 points in the fourth quarter.
Lithuania's head coach Marius Linartas conceded the game had been tougher than he had imagined.
"This was a very difficult game. Maybe it was more difficult because of our easy win over Israel yesterday. I am just glad that we won and this can only be a good experience to learn from ahead of the next round."
Lithuania took a 24-19 lead at the end of the first quarter but couldn't quite shake free as Russia kept closing the gap.
Pavel Antipov - who had a monster game with a game-high 25 points and nine rebounds - hit a three-pointer to cut the deficit to two, 38-36, but Lithuania finished the half on an 11-2 run with Deividias Nazarovas accounting for five of those points.
Surprisingly, Russia only led only once, when Gleb Plotnikov made a pair of free-throws late in the first quarter for a 19-18 score. Lithuania though jumped right back in front on Giedrius Staniulis' monster dunk as they took a 24-19 advantage heading into the second quarter.
Valanciunas also had 15 rebounds and five blocks.