After the game, GB Futures coach Paul Mokeski focused on how far his players had come as they won the three-game series 2-1, saying: "We came together in a short week and the guys did a really good job, they played hard and pulled together as a team.
"The future of Great Britain basketball is based on the Futures programme so these guys will be looking to be on the main stage with the senior team in the next two or three years," Mokeski added.
After a slow opening, Kyle Johnson got the ball rolling with an open three from the baseline but it was the Lithuanians who started the stronger of the two sides in the opening three minutes, as they were out-rebounding GB and being more aggressive inside.
A three by Ben Mockford and a bucket from Ogo Adegboye though gave the Futures a 14-10 lead with 4:19 remaining in the first and they extended their lead, by moving 19-12 ahead after the first quarter.
An open two-hand dunk from Ovie Soko to start the second period extended the GB Futures lead to nine but the visitors fought back to tie the game at 23 thanks to foul shots from Paulius Dambrauskas. At half-time the GB Futures were behind 36-31 as the competitive edge of their Lithuanian counterparts shone through in the final three minutes of the half.
The GB Futures started the third exceptionally though, and a lay-up from Johnson gave his side a 37-36.
The third quarter was a back-and-forth affair as Lithuania again had their noses in-front 53-50 headed to the last ten minutes.
Points from Myles Hesson and Adegboye gave the Futures a 54-53 lead to begin the fourth, but the visitors came back and led 63-58 with just over four minutes left.
Matthew Bryan-Amaning though inspired a fightback for the Futures as he tied the game at 63 with a three-point play and with seconds left Andrew Lawrence had the chance to win it for GB, but his three missed at the buzzer and the Lithuanians took the win.
GB Futures player Kyle Johnson commented on the defeat: "We are a little disappointed because we wanted to come out and win. We were the better team over the week, we prepared really hard for these games but we came out today a little sluggish and it hurt in the long run."
Augustas Peciukevicius led Lithuania's Under-21 side with 24 points.