Great Britain's losing start to World Cup qualifying stretched to two matches as they were beaten 73-70 by Group H bottom seeds Estonia in Tallinn.
Ovie Soko led GB's scoring with 17 points - nine of which came from free throws - and Myles Hesson added 14.
Tony Garbelotto's side had a chance to tie with the game's last shot, but Dan Clark missed a three-pointer.
"Maybe we should have expected this, but we didn't play as well as we did against Greece," said Garbelotto.
"I'm a little disappointed."
The squad will reassemble in February for away ties in Israel and Greece.
"I've always felt that we were good enough to beat Israel and this team two times," Garbelotto said.
"The only positive is we were eight points down and we somehow came back. But we never really threatened to put them under pressure. We looked really disjointed."
Britain had opened their campaign with a 95-92 overtime loss to Greece in Leicester.
After that near miss they looked keen to make amends, with their bench players sparking a 9-2 run that gave them a 24-18 first-quarter lead.
That vanished in the first seven minutes of a second quarter in which Estonia found their range, hitting five three-pointers to lead by eight points at half-time.
GB closed that threat down in the third quarter, but still struggled to score consistently after Luke Nelson and Will Saunders hit threes.
Trailing by two points going into the final quarter, GB scored only three free throws in the first six minutes, while still holding their hosts to just eight points.
Hesson, who broke the drought with a tip-in, added another to bring GB to within two points, but was fouled out of the game after Estonia scored the next two baskets to lead 72-66.
GB chipped away at the lead with free throws - two each from Soko and Tarik Phillip had them trailing 73-70 with 14 seconds remaining.
But though they regained possession, Clark's touch deserted him in the dying seconds.