McKay was in good form for GB on her return from a knee injury
Great Britain suffered a 60-55 defeat to Finland, which leaves their future in European Division A, and their hopes for the 2012 Olympics, in jeopardy.
Sarah McKay, restored to the team after missing two games, scored 15 points and Rose Mason added 11.
GB took the first quarter 17-12 and, after losing that advantage, were ahead 49-47 going into the final 10 minutes.
But they scored just six more points as Finland finished the stronger to avenge their home defeat nine days ago.
After their second loss in four days, Great Britain now have to win away from home, in Romania and Bosnia and hope the Finns either slip up in their two home games against the same opposition or fail to beat Romania by large margin.
If GB do slip into the B Division, they are virtually certain to miss out on playing as hosts in the 2012 Olympics.
With McKay back in the starting line-up after resting her knee for Saturday's game against Romania, GB had the better of the early exchanges.
This team doesn't want to be a B Division team
GB coach Mark Clark
They led 17-12 at the end of the third quarter with Lisa Hutchinson and Kristy Lavin both scoring five points.
In the second quarter, the Finns made the most of some careless use of the ball by GB, coming back to take the lead 31-29 on a three from Heeta Korpivaara.
GB went in 33-31 ahead thanks to Stef Collins' three-pointer with five seconds remaining.
Both teams missed opportunities in the third quarter as the tension of the occasion began to tell.
And they struggled to score in the fourth quarter, with Finland finding points from two previously scoreless players, Vilma Kesanen and Kaiba Tuure, to lead 55-54 with 2:25 remaining.
In the last two minutes, GB's misses finally brought them down. Hutchinson missed a lay-up and Lavin missed a three-pointer, despite Butler's offensive rebound in between.
Video diary - meet the GB women's basketball team
At the other end, Kesanen drilled a three to give Finland a 58-54 lead and ignite the celebrations on their bench.
GB then missed on their next possession through Collins and Mason and although McKay hit a single free throw with 25 seconds left it provided little hope.
GB coach Mark Clark was disconsolate after the defeat.
"Maybe we let the pressure of the game get to us," he said.
"We didn't shoot a great percentage inside and I'd expect us to finish our plays a lot better. We looked a tired team at times. This number of games in such a short time is tough."
"It's never over till it's over. This team doesn't want to be a B Division team. Only we have the answer now."
Bookmark with:
What are these?