Gravelines and their American star Tyson Wheeler suffered EuroCup heartbreak in their Group H opener on Tuesday as Dynamo Moscow Region won 91-88 in overtime.
Playing before their own fans, Gravelines found themselves at the free throw line with five seconds to play in regulation and the game tied at 82-82.
Wheeler, one of his team's main offensive weapons, missed both attempts, and the contest went to overtime.
In the extra period, Sam Hoskin made one of two from the line with 25 seconds to play to set up a thrilling finish.
Gravelines brought the ball up the floor needing just a shot inside in the arc to go back in front.
They allowed the clock to tick down to four seconds, and Wheeler launched another three-pointer.
Sadly for the home fans, his shot was off the mark and Russian international Nikita Morgunov grabbed the rebound for Dynamo Moscow Region.
Gravelines fouled Stevin Smith to stop the clock with one second remaining, and he made both for a three-point lead - the final margin.
The defeat ruined an excellent night for Dainius Adomaitis, who led Gravelines with 26 points and eight rebounds.
Samuel Hoskin had 23 for the visitors from Russia.
Dynamo Moscow Region dominated the boards in this game, out-rebounding their hosts 45-29.
Gravelines were a woeful 60% from the free throw line, converting just 14 of 23 attempts.