Flinder Boyd impressed for GB, here taking on Turkey's Omer Onan
Despite an improved performance, Great Britain were edged out 70-63 by Turkey in their second outing at the O2 Arena.
Small forward Nick George led GB's scoring with 11 points and Joel Freeland and Dan Clark added nine each.
GB stayed with Turkey throughout the game and only a shortage of firepower, and the experience of Turkey's NBA star Hedo Turkoglu, saw GB come up short.
Turkey scored their last 13 points from the free throw line, seven of those from Turkoglu, who had 15 points.
Against probably the best team in the tournament, GB started solidly and improved when first-choice playmaker Flinder Boyd, missing from Friday's opening defeat to Poland, was brought on in the first quarter.
Freeland was again a force for GB, drawing two of the three fouls that forced Turkoglu out of the game early on.
Trailing by three points at half-time (33-30), GB took the lead with a three-pointer from Nate Reinking at the start of what proved to be a fractious third quarter.
First, Turkey coach Bogdan Tanjevic was ejected on two technical fouls for dissent.
Two minutes later, players from both sides had to be pulled apart after an altercation between GB's Justin Robinson and Turkey's Omer Asik.
GB had threes from Kieron Achara and George to open the fourth quarter and trailed by just a single point with 3:46 remaining.
But that was as close as GB managed to get as The Turks took advantage of GB's missed shots and punished them from the free throw line.
Earlier in the day, Israel defeated Poland 86-72 to leave both sides with a win each.
Poland face Turkey then GB take on Israel on Sunday's final day of action.