Top seeds Jamie Murray and John-Patrick Smith lost in the doubles final of the inaugural Murray Trophy in Glasgow to Ruben Bemelmans and Daniel Masur.
The Belgian-German pair prevailed 4-6 6-3 10-8, sealing victory via a champions tie-break.
Murray, playing with Australian Smith, was the last Briton remaining in the seven-day ATP Challenger tournament he has worked with the LTA to curate.
"It's been an amazing week of tennis," the 33-year-old said.
"I wanted to give people the chance to come out and watch tennis in Scotland and get to experience a live professional tennis event.
"I'm disappointed to lose the final but the guys played well, came back strong in the second set and held their nerve well in the tie-break. It was a good level match."
Later on Sunday, Finland's Emil Ruusuvuori beat Frenchman Alexandre Muller 6-3 6-1 to win the singles title and claim his third ATP crown of the season.