Great Britain need a win against Israel on Monday to reach the second round of the EuroBasket finals after a 60-45 defeat to the Czech Republic.
Despite trailing at the end of the opening quarter, the Czechs - ranked second in the world - went on to dominate the game.
Johannah Leedham led GB with 14 points.
GB coach Tom Maher said: "Playing against a team with the star-studded quality they've got, I think it was a pretty good result."
Maher told BBC Sport: "Over the last two games, I've been impressed with the poise the players have shown, they haven't looked like 'deer in the headlights'.
"Generally, our mentality has been very good and we've fought hard."
Czech Republic, who were runners-up in the world championships last year, struggled to contain a lively GB team in the first quarter as the EuroBasket debutants took the lead.
Some solid GB defensive play restricted the Czechs to just nine points in the opening quarter.
Despite only just returning from a knee injury, star player Leedham had an impressive game, sinking seven of GB's 13 points in the opener, including a basket from the arc.
But Leedham's appearances were intermittent due to a lack of fitness and this proved to be GB's downfall as the team lacked scoring options whenever the Liverpudlian was on the bench.
"She doesn't have that depth in conditioning," Maher said. "To run her into the ground tonight wouldn't have made any sense so we had to rely on the other players."
Midway through the second period, Czech Republic overcame any early nerves to assert their authority on the game.
Katerina Elhotova led proceedings with a succession of baskets, on her way to 27 on the night, as her side took a 25-18 lead.
Ros Mason's introduction in the latter part of the third boosted GB's offence somewhat but they lacked the potency of their Czech opponents, who sunk 37% of their two-point shots compared to GB's 21%.
A sixth three-pointer of the night from Elhotova late in the final stanza put the game out of reach as the Czechs widened the deficit to 52-37.
A second defeat in two days for GB means they need a win against Israel on Monday to ensure they finish in the top three of their group and reach the next round.
With Israel chasing the same result, Maher admits the game will be make or break: "Of course it puts pressure on you. You can't pretend it doesn't. But it's how you handle it, that's the test."
"Israel play a very similar style game to us but they're more offence-minded because they've built their game around their shooters.
"It will be interesting. It will come down to whether we can defend their shooters."
In the other group B game, Belarus beat Israel 68-41.
Watch GB women in their final group game vs. Israel on Monday 20t June live on BBC Red Button and the BBC Sport website from 1400 BST.