Britain came close to winning its first Olympic game since 1948 but Splitter, who plays with the San Antonio Spurs, hit a key layup off a pinpoint pass in traffic from Marcelinho Huertas to make it 65-59.
Luol Deng was then fouled on a three-point attempt, but hit only one of his free throws. Britain did not foul and Brazil ran 20 seconds off the clock before Deng fouled Huertas — who sank two free throws with 11 seconds left to seal the game.
Huertas finished with 13 points and eight assists.
Nate Reinking scored 13 points for Britain.