Andy Murray was unable to cap a strong week in the Middle East with a win as he lost the Mubadala World Tennis Championship final in straight sets to Andrey Rublev.
The Russian world number five won 6-4 7-6 (7-2) to secure the title at the exhibition event in Abu Dhabi.
Murray, 34, battled back in the second set, but faltered in the tie-break.
He had beaten fellow Briton Dan Evans and 20-time Grand Slam champion Rafael Nadal to reach the final.
Rublev controlled much of the first set and got the decisive break of serve in the fifth game.
The 24-year-old then broke the Scot in the first game of the second but his serve temporarily deserted him as he hit three double faults during the eighth game, allowing Murray to break back with a superb backhand winner.
Rublev managed to compose himself and held to love to force the tie-break, which he won comfortably as Murray's challenge ran out of steam.
Despite the defeat, Murray said he was optimistic as he continues to try and reignite his career after having two major hip operations.
"I have been pretty healthy over the last three months, I've got to play a lot of matches," said the three-time Grand Slam winner, who is working with coach Jan de Witt after his split with Jamie Delgado.
"I just need to find a way of turning some of these matches against the top players around and hopefully I can have some big runs in the biggest tournaments again, that's my goal.
"I'm trying as hard as I can to do that."
Murray is preparing to play in the Australian Open for the first time since 2018 with the first Grand Slam of 2022 starting in Melbourne on 17 January.
Earlier, Canadian Denis Shapovalov beat Nadal 6-7 (4-7) 6-3 10-6 in the third-place play-off with the Spaniard returning to tennis in Abu Dhabi, having not played since August because of a foot injury.