Lithuania is undefeated thus far, tallying wins against Brazil and Argentina (who just finished an unbelievable double OT game). They are an incredibly balanced team, with six players averaging over 7 points.
Spain definitely has more talent, but have underperformed all Olympics, suffering losses to Brazil and Croatia. Pau Gasol has been their best player, averaging 18 per game. But Lithuania's Jonas Valanciunas (starting center for the Raptors) should be able to limit Gasol inside.
Look for Lithuania to keep the game within 3 tonight in Rio.